diff --git a/src/hb-aat-layout.cc b/src/hb-aat-layout.cc
index caff204d6..e06d286ff 100644
--- a/src/hb-aat-layout.cc
+++ b/src/hb-aat-layout.cc
@@ -229,7 +229,7 @@ hb_aat_layout_compile_map (const hb_aat_map_builder_t *mapper,
  *
  * <note>Note: does not examine the `GSUB` table.</note>
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 2.3.0
  */
@@ -300,7 +300,7 @@ hb_aat_layout_remove_deleted_glyphs (hb_buffer_t *buffer)
  *
  * <note>Note: does not examine the `GPOS` table.</note>
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 2.3.0
  */
@@ -333,7 +333,7 @@ hb_aat_layout_position (const hb_ot_shape_plan_t *plan,
  * Tests whether the specified face includes any tracking information
  * in the `trak` table.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 2.3.0
  */
diff --git a/src/hb-blob.cc b/src/hb-blob.cc
index b561a9374..85636f3b7 100644
--- a/src/hb-blob.cc
+++ b/src/hb-blob.cc
@@ -99,7 +99,7 @@ hb_blob_create (const char        *data,
  * is zero. This is in contrast to hb_blob_create(), which returns the singleton
  * empty blob (as returned by hb_blob_get_empty()) if @length is zero.
  *
- * Return value: New blob, or %NULL if failed.  Destroy with hb_blob_destroy().
+ * Return value: New blob, or `NULL` if failed.  Destroy with hb_blob_destroy().
  *
  * Since: 2.8.2
  **/
@@ -278,7 +278,7 @@ hb_blob_destroy (hb_blob_t *blob)
  *
  * Attaches a user-data key/data pair to the specified blob.
  *
- * Return value: %true if success, %false otherwise
+ * Return value: `true` if success, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -335,7 +335,7 @@ hb_blob_make_immutable (hb_blob_t *blob)
  *
  * Tests whether a blob is immutable.
  *
- * Return value: %true if @blob is immutable, %false otherwise
+ * Return value: `true` if @blob is immutable, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -394,7 +394,7 @@ hb_blob_get_data (hb_blob_t *blob, unsigned int *length)
  * fails.
  *
  * Returns: (transfer none) (array length=length): Writable blob data,
- * or %NULL if failed.
+ * or `NULL` if failed.
  *
  * Since: 0.9.2
  **/
@@ -620,7 +620,7 @@ hb_blob_create_from_file (const char *file_name)
  * specified binary font file.
  *
  * Returns: An #hb_blob_t pointer with the content of the file,
- * or %NULL if failed.
+ * or `NULL` if failed.
  *
  * Since: 2.8.2
  **/
diff --git a/src/hb-buffer-serialize.cc b/src/hb-buffer-serialize.cc
index 3f619a113..d1e177543 100644
--- a/src/hb-buffer-serialize.cc
+++ b/src/hb-buffer-serialize.cc
@@ -56,7 +56,7 @@ hb_buffer_serialize_list_formats ()
 /**
  * hb_buffer_serialize_format_from_string:
  * @str: (array length=len) (element-type uint8_t): a string to parse
- * @len: length of @str, or -1 if string is %NULL terminated
+ * @len: length of @str, or -1 if string is `NULL` terminated
  *
  * Parses a string into an #hb_buffer_serialize_format_t. Does not check if
  * @str is a valid buffer serialization format, use
@@ -78,11 +78,11 @@ hb_buffer_serialize_format_from_string (const char *str, int len)
  * hb_buffer_serialize_format_to_string:
  * @format: an #hb_buffer_serialize_format_t to convert.
  *
- * Converts @format to the string corresponding it, or %NULL if it is not a valid
+ * Converts @format to the string corresponding it, or `NULL` if it is not a valid
  * #hb_buffer_serialize_format_t.
  *
  * Return value: (transfer none):
- * A %NULL terminated string corresponding to @format. Should not be freed.
+ * A `NULL` terminated string corresponding to @format. Should not be freed.
  *
  * Since: 0.9.7
  **/
@@ -400,9 +400,9 @@ _hb_buffer_serialize_unicode_text (hb_buffer_t *buffer,
  * @buf: (out) (array length=buf_size) (element-type uint8_t): output string to
  *       write serialized buffer into.
  * @buf_size: the size of @buf.
- * @buf_consumed: (out) (optional): if not %NULL, will be set to the number of bytes written into @buf.
+ * @buf_consumed: (out) (optional): if not `NULL`, will be set to the number of bytes written into @buf.
  * @font: (nullable): the #hb_font_t used to shape this buffer, needed to
- *        read glyph names and extents. If %NULL, an empty font will be used.
+ *        read glyph names and extents. If `NULL`, an empty font will be used.
  * @format: the #hb_buffer_serialize_format_t to use for formatting the output.
  * @flags: the #hb_buffer_serialize_flags_t that control what glyph properties
  *         to serialize.
@@ -514,7 +514,7 @@ hb_buffer_serialize_glyphs (hb_buffer_t *buffer,
  * @buf: (out) (array length=buf_size) (element-type uint8_t): output string to
  *       write serialized buffer into.
  * @buf_size: the size of @buf.
- * @buf_consumed: (out) (optional): if not %NULL, will be set to the number of bytes written into @buf.
+ * @buf_consumed: (out) (optional): if not `NULL`, will be set to the number of bytes written into @buf.
  * @format: the #hb_buffer_serialize_format_t to use for formatting the output.
  * @flags: the #hb_buffer_serialize_flags_t that control what glyph properties
  *         to serialize.
@@ -637,9 +637,9 @@ _hb_buffer_serialize_invalid (hb_buffer_t *buffer,
  * @buf: (out) (array length=buf_size) (element-type uint8_t): output string to
  *       write serialized buffer into.
  * @buf_size: the size of @buf.
- * @buf_consumed: (out) (optional): if not %NULL, will be set to the number of bytes written into @buf.
+ * @buf_consumed: (out) (optional): if not `NULL`, will be set to the number of bytes written into @buf.
  * @font: (nullable): the #hb_font_t used to shape this buffer, needed to
- *        read glyph names and extents. If %NULL, an empty font will be used.
+ *        read glyph names and extents. If `NULL`, an empty font will be used.
  * @format: the #hb_buffer_serialize_format_t to use for formatting the output.
  * @flags: the #hb_buffer_serialize_flags_t that control what glyph properties
  *         to serialize.
@@ -727,7 +727,7 @@ parse_hex (const char *pp, const char *end, uint32_t *pv)
  * hb_buffer_deserialize_glyphs:
  * @buffer: an #hb_buffer_t buffer.
  * @buf: (array length=buf_len): string to deserialize
- * @buf_len: the size of @buf, or -1 if it is %NULL-terminated
+ * @buf_len: the size of @buf, or -1 if it is `NULL`-terminated
  * @end_ptr: (out) (optional): output pointer to the character after last
  *                               consumed one.
  * @font: (nullable): font for getting glyph IDs
@@ -736,7 +736,7 @@ parse_hex (const char *pp, const char *end, uint32_t *pv)
  * Deserializes glyphs @buffer from textual representation in the format
  * produced by hb_buffer_serialize_glyphs().
  *
- * Return value: %true if @buf is not fully consumed, %false otherwise.
+ * Return value: `true` if @buf is not fully consumed, `false` otherwise.
  *
  * Since: 0.9.7
  **/
@@ -800,7 +800,7 @@ hb_buffer_deserialize_glyphs (hb_buffer_t *buffer,
  * hb_buffer_deserialize_unicode:
  * @buffer: an #hb_buffer_t buffer.
  * @buf: (array length=buf_len): string to deserialize
- * @buf_len: the size of @buf, or -1 if it is %NULL-terminated
+ * @buf_len: the size of @buf, or -1 if it is `NULL`-terminated
  * @end_ptr: (out) (optional): output pointer to the character after last
  *                               consumed one.
  * @format: the #hb_buffer_serialize_format_t of the input @buf
@@ -808,7 +808,7 @@ hb_buffer_deserialize_glyphs (hb_buffer_t *buffer,
  * Deserializes Unicode @buffer from textual representation in the format
  * produced by hb_buffer_serialize_unicode().
  *
- * Return value: %true if @buf is not fully consumed, %false otherwise.
+ * Return value: `true` if @buf is not fully consumed, `false` otherwise.
  *
  * Since: 2.7.3
  **/
diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index 2272ecf09..fddda2330 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -51,7 +51,7 @@
  * Checks the equality of two #hb_segment_properties_t's.
  *
  * Return value:
- * %true if all properties of @a equal those of @b, %false otherwise.
+ * `true` if all properties of @a equal those of @b, `false` otherwise.
  *
  * Since: 0.9.7
  **/
@@ -643,9 +643,9 @@ DEFINE_NULL_INSTANCE (hb_buffer_t) =
  * Return value: (transfer full):
  * A newly allocated #hb_buffer_t with a reference count of 1. The initial
  * reference count should be released with hb_buffer_destroy() when you are done
- * using the #hb_buffer_t. This function never returns %NULL. If memory cannot
+ * using the #hb_buffer_t. This function never returns `NULL`. If memory cannot
  * be allocated, a special #hb_buffer_t object will be returned on which
- * hb_buffer_allocation_successful() returns %false.
+ * hb_buffer_allocation_successful() returns `false`.
  *
  * Since: 0.9.2
  **/
@@ -775,7 +775,7 @@ hb_buffer_destroy (hb_buffer_t *buffer)
  *
  * Attaches a user-data key/data pair to the specified buffer. 
  *
- * Return value: %true if success, %false otherwise
+ * Return value: `true` if success, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1278,7 +1278,7 @@ hb_buffer_clear_contents (hb_buffer_t *buffer)
  * Pre allocates memory for @buffer to fit at least @size number of items.
  *
  * Return value:
- * %true if @buffer memory allocation succeeded, %false otherwise
+ * `true` if @buffer memory allocation succeeded, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1295,7 +1295,7 @@ hb_buffer_pre_allocate (hb_buffer_t *buffer, unsigned int size)
  * Check if allocating memory for the buffer succeeded.
  *
  * Return value:
- * %true if @buffer memory allocation succeeded, %false otherwise.
+ * `true` if @buffer memory allocation succeeded, `false` otherwise.
  *
  * Since: 0.9.2
  **/
@@ -1340,7 +1340,7 @@ hb_buffer_add (hb_buffer_t    *buffer,
  * end.
  *
  * Return value:
- * %true if @buffer memory allocation succeeded, %false otherwise.
+ * `true` if @buffer memory allocation succeeded, `false` otherwise.
  *
  * Since: 0.9.2
  **/
@@ -1426,7 +1426,7 @@ hb_buffer_get_glyph_infos (hb_buffer_t  *buffer,
  * If buffer did not have positions before, the positions will be
  * initialized to zeros, unless this function is called from
  * within a buffer message callback (see hb_buffer_set_message_func()),
- * in which case %NULL is returned.
+ * in which case `NULL` is returned.
  *
  * Return value: (transfer none) (array length=length):
  * The @buffer glyph position array.
@@ -1461,7 +1461,7 @@ hb_buffer_get_glyph_positions (hb_buffer_t  *buffer,
  * and cleared of position data when hb_buffer_clear_contents() is called.
  *
  * Return value:
- * %true if the @buffer has position array, %false otherwise.
+ * `true` if the @buffer has position array, `false` otherwise.
  *
  * Since: 2.7.3
  **/
@@ -1645,10 +1645,10 @@ hb_buffer_add_utf (hb_buffer_t  *buffer,
  * @buffer: An #hb_buffer_t
  * @text: (array length=text_length) (element-type uint8_t): An array of UTF-8
  *               characters to append.
- * @text_length: The length of the @text, or -1 if it is %NULL terminated.
+ * @text_length: The length of the @text, or -1 if it is `NULL` terminated.
  * @item_offset: The offset of the first character to add to the @buffer.
  * @item_length: The number of characters to add to the @buffer, or -1 for the
- *               end of @text (assuming it is %NULL terminated).
+ *               end of @text (assuming it is `NULL` terminated).
  *
  * See hb_buffer_add_codepoints().
  *
@@ -1671,10 +1671,10 @@ hb_buffer_add_utf8 (hb_buffer_t  *buffer,
  * hb_buffer_add_utf16:
  * @buffer: An #hb_buffer_t
  * @text: (array length=text_length): An array of UTF-16 characters to append
- * @text_length: The length of the @text, or -1 if it is %NULL terminated
+ * @text_length: The length of the @text, or -1 if it is `NULL` terminated
  * @item_offset: The offset of the first character to add to the @buffer
  * @item_length: The number of characters to add to the @buffer, or -1 for the
- *               end of @text (assuming it is %NULL terminated)
+ *               end of @text (assuming it is `NULL` terminated)
  *
  * See hb_buffer_add_codepoints().
  *
@@ -1697,10 +1697,10 @@ hb_buffer_add_utf16 (hb_buffer_t    *buffer,
  * hb_buffer_add_utf32:
  * @buffer: An #hb_buffer_t
  * @text: (array length=text_length): An array of UTF-32 characters to append
- * @text_length: The length of the @text, or -1 if it is %NULL terminated
+ * @text_length: The length of the @text, or -1 if it is `NULL` terminated
  * @item_offset: The offset of the first character to add to the @buffer
  * @item_length: The number of characters to add to the @buffer, or -1 for the
- *               end of @text (assuming it is %NULL terminated)
+ *               end of @text (assuming it is `NULL` terminated)
  *
  * See hb_buffer_add_codepoints().
  *
@@ -1724,10 +1724,10 @@ hb_buffer_add_utf32 (hb_buffer_t    *buffer,
  * @buffer: An #hb_buffer_t
  * @text: (array length=text_length) (element-type uint8_t): an array of UTF-8
  *               characters to append
- * @text_length: the length of the @text, or -1 if it is %NULL terminated
+ * @text_length: the length of the @text, or -1 if it is `NULL` terminated
  * @item_offset: the offset of the first character to add to the @buffer
  * @item_length: the number of characters to add to the @buffer, or -1 for the
- *               end of @text (assuming it is %NULL terminated)
+ *               end of @text (assuming it is `NULL` terminated)
  *
  * Similar to hb_buffer_add_codepoints(), but allows only access to first 256
  * Unicode code points that can fit in 8-bit strings.
@@ -1750,10 +1750,10 @@ hb_buffer_add_latin1 (hb_buffer_t   *buffer,
  * hb_buffer_add_codepoints:
  * @buffer: a #hb_buffer_t to append characters to.
  * @text: (array length=text_length): an array of Unicode code points to append.
- * @text_length: the length of the @text, or -1 if it is %NULL terminated.
+ * @text_length: the length of the @text, or -1 if it is `NULL` terminated.
  * @item_offset: the offset of the first code point to add to the @buffer.
  * @item_length: the number of code points to add to the @buffer, or -1 for the
- *               end of @text (assuming it is %NULL terminated).
+ *               end of @text (assuming it is `NULL` terminated).
  *
  * Appends characters from @text array to @buffer. The @item_offset is the
  * position of the first character from @text that will be appended, and
diff --git a/src/hb-buffer.h b/src/hb-buffer.h
index 22fb3496f..e095c5344 100644
--- a/src/hb-buffer.h
+++ b/src/hb-buffer.h
@@ -755,16 +755,16 @@ hb_buffer_diff (hb_buffer_t *buffer,
  * hb_buffer_message_func_t:
  * @buffer: An #hb_buffer_t to work upon
  * @font: The #hb_font_t the @buffer is shaped with
- * @message: %NULL-terminated message passed to the function
+ * @message: `NULL`-terminated message passed to the function
  * @user_data: User data pointer passed by the caller
  *
  * A callback method for #hb_buffer_t. The method gets called with the
  * #hb_buffer_t it was set on, the #hb_font_t the buffer is shaped with and a
  * message describing what step of the shaping process will be performed.
- * Returning %false from this method will skip this shaping step and move to
+ * Returning `false` from this method will skip this shaping step and move to
  * the next one.
  *
- * Return value: %true to perform the shaping step, %false to skip it.
+ * Return value: `true` to perform the shaping step, `false` to skip it.
  *
  * Since: 1.1.3
  */
diff --git a/src/hb-common.cc b/src/hb-common.cc
index 7266d9b01..80f36feea 100644
--- a/src/hb-common.cc
+++ b/src/hb-common.cc
@@ -108,7 +108,7 @@ _hb_options_init ()
 /**
  * hb_tag_from_string:
  * @str: (array length=len) (element-type uint8_t): String to convert
- * @len: Length of @str, or -1 if it is %NULL-terminated
+ * @len: Length of @str, or -1 if it is `NULL`-terminated
  *
  * Converts a string into an #hb_tag_t. Valid tags
  * are four characters. Shorter input strings will be
@@ -170,7 +170,7 @@ static const char direction_strings[][4] = {
 /**
  * hb_direction_from_string:
  * @str: (array length=len) (element-type uint8_t): String to convert
- * @len: Length of @str, or -1 if it is %NULL-terminated
+ * @len: Length of @str, or -1 if it is `NULL`-terminated
  *
  * Converts a string to an #hb_direction_t.
  *
@@ -357,7 +357,7 @@ retry:
  * hb_language_from_string:
  * @str: (array length=len) (element-type uint8_t): a string representing
  *       a BCP 47 language tag
- * @len: length of the @str, or -1 if it is %NULL-terminated.
+ * @len: length of the @str, or -1 if it is `NULL`-terminated.
  *
  * Converts @str representing a BCP 47 language tag to the corresponding
  * #hb_language_t.
@@ -396,7 +396,7 @@ hb_language_from_string (const char *str, int len)
  * Converts an #hb_language_t to a string.
  *
  * Return value: (transfer none):
- * A %NULL-terminated string representing the @language. Must not be freed by
+ * A `NULL`-terminated string representing the @language. Must not be freed by
  * the caller.
  *
  * Since: 0.9.2
@@ -498,7 +498,7 @@ hb_script_from_iso15924_tag (hb_tag_t tag)
  * hb_script_from_string:
  * @str: (array length=len) (element-type uint8_t): a string representing an
  *       ISO 15924 tag.
- * @len: length of the @str, or -1 if it is %NULL-terminated.
+ * @len: length of the @str, or -1 if it is `NULL`-terminated.
  *
  * Converts a string @str representing an ISO 15924 script tag to a
  * corresponding #hb_script_t. Shorthand for hb_tag_from_string() then
@@ -693,8 +693,8 @@ hb_version_string ()
  * Tests the library version against a minimum value,
  * as three integer components.
  *
- * Return value: %true if the library is equal to or greater than
- * the test value, %false otherwise
+ * Return value: `true` if the library is equal to or greater than
+ * the test value, `false` otherwise
  *
  * Since: 0.9.30
  **/
@@ -881,7 +881,7 @@ parse_one_feature (const char **pp, const char *end, hb_feature_t *feature)
 /**
  * hb_feature_from_string:
  * @str: (array length=len) (element-type uint8_t): a string to parse
- * @len: length of @str, or -1 if string is %NULL terminated
+ * @len: length of @str, or -1 if string is `NULL` terminated
  * @feature: (out): the #hb_feature_t to initialize with the parsed values
  *
  * Parses a string into a #hb_feature_t.
@@ -923,7 +923,7 @@ parse_one_feature (const char **pp, const char *end, hb_feature_t *feature)
  * </informaltable>
  *
  * Return value:
- * %true if @str is successfully parsed, %false otherwise
+ * `true` if @str is successfully parsed, `false` otherwise
  *
  * Since: 0.9.5
  **/
@@ -954,7 +954,7 @@ hb_feature_from_string (const char *str, int len,
  * @buf: (array length=size) (out): output string
  * @size: the allocated size of @buf
  *
- * Converts a #hb_feature_t into a %NULL-terminated string in the format
+ * Converts a #hb_feature_t into a `NULL`-terminated string in the format
  * understood by hb_feature_from_string(). The client in responsible for
  * allocating big enough size for @buf, 128 bytes is more than enough.
  *
@@ -1022,7 +1022,7 @@ parse_one_variation (const char **pp, const char *end, hb_variation_t *variation
 /**
  * hb_variation_from_string:
  * @str: (array length=len) (element-type uint8_t): a string to parse
- * @len: length of @str, or -1 if string is %NULL terminated
+ * @len: length of @str, or -1 if string is `NULL` terminated
  * @variation: (out): the #hb_variation_t to initialize with the parsed values
  *
  * Parses a string into a #hb_variation_t.
@@ -1035,7 +1035,7 @@ parse_one_variation (const char **pp, const char *end, hb_variation_t *variation
  * number. For example `wght=500`, or `slnt=-7.5`.
  *
  * Return value:
- * %true if @str is successfully parsed, %false otherwise
+ * `true` if @str is successfully parsed, `false` otherwise
  *
  * Since: 1.4.2
  */
@@ -1107,7 +1107,7 @@ get_C_locale ()
  * @buf: (array length=size) (out): output string
  * @size: the allocated size of @buf
  *
- * Converts an #hb_variation_t into a %NULL-terminated string in the format
+ * Converts an #hb_variation_t into a `NULL`-terminated string in the format
  * understood by hb_variation_from_string(). The client in responsible for
  * allocating big enough size for @buf, 128 bytes is more than enough.
  *
diff --git a/src/hb-deprecated.h b/src/hb-deprecated.h
index a130d77f7..333dc3cd4 100644
--- a/src/hb-deprecated.h
+++ b/src/hb-deprecated.h
@@ -93,7 +93,7 @@ HB_BEGIN_DECLS
  * This method should retrieve the glyph ID for a specified Unicode code point
  * font, with an optional variation selector.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  * Deprecated: 1.2.3
  *
  **/
diff --git a/src/hb-draw.cc b/src/hb-draw.cc
index fdc71102d..74952b954 100644
--- a/src/hb-draw.cc
+++ b/src/hb-draw.cc
@@ -137,7 +137,7 @@ HB_DRAW_FUNCS_IMPLEMENT_CALLBACKS
  * Return value: (transfer full):
  * A newly allocated #hb_draw_funcs_t with a reference count of 1. The initial
  * reference count should be released with hb_draw_funcs_destroy when you are
- * done using the #hb_draw_funcs_t. This function never returns %NULL. If
+ * done using the #hb_draw_funcs_t. This function never returns `NULL`. If
  * memory cannot be allocated, a special singleton #hb_draw_funcs_t object will
  * be returned.
  *
@@ -234,7 +234,7 @@ hb_draw_funcs_make_immutable (hb_draw_funcs_t *dfuncs)
  *
  * Checks whether @dfuncs is immutable.
  *
- * Return value: %true if @dfuncs is immutable, %false otherwise
+ * Return value: `true` if @dfuncs is immutable, `false` otherwise
  *
  * Since: 4.0.0
  **/
diff --git a/src/hb-face.cc b/src/hb-face.cc
index 7cdd6cb49..8f8b1a6d1 100644
--- a/src/hb-face.cc
+++ b/src/hb-face.cc
@@ -315,7 +315,7 @@ hb_face_destroy (hb_face_t *face)
  *
  * Attaches a user-data key/data pair to the given face object.
  *
- * Return value: %true if success, %false otherwise
+ * Return value: `true` if success, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -371,7 +371,7 @@ hb_face_make_immutable (hb_face_t *face)
  *
  * Tests whether the given face object is immutable.
  *
- * Return value: %true is @face is immutable, %false otherwise
+ * Return value: `true` is @face is immutable, `false` otherwise
  *
  * Since: 0.9.2
  **/
diff --git a/src/hb-font.cc b/src/hb-font.cc
index 8d3521c86..0811621d1 100644
--- a/src/hb-font.cc
+++ b/src/hb-font.cc
@@ -754,7 +754,7 @@ hb_font_funcs_destroy (hb_font_funcs_t *ffuncs)
  *
  * Attaches a user-data key/data pair to the specified font-functions structure.
  *
- * Return value: %true if success, %false otherwise
+ * Return value: `true` if success, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -811,7 +811,7 @@ hb_font_funcs_make_immutable (hb_font_funcs_t *ffuncs)
  *
  * Tests whether a font-functions structure is immutable.
  *
- * Return value: %true if @ffuncs is immutable, %false otherwise
+ * Return value: `true` if @ffuncs is immutable, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -903,7 +903,7 @@ hb_font_t::has_func (unsigned int i)
  * Fetches the extents for a specified font, for horizontal
  * text segments.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 1.1.3
  **/
@@ -922,7 +922,7 @@ hb_font_get_h_extents (hb_font_t         *font,
  * Fetches the extents for a specified font, for vertical
  * text segments.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 1.1.3
  **/
@@ -946,7 +946,7 @@ hb_font_get_v_extents (hb_font_t         *font,
  * If @variation_selector is 0, calls hb_font_get_nominal_glyph();
  * otherwise calls hb_font_get_variation_glyph().
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -974,7 +974,7 @@ hb_font_get_glyph (hb_font_t      *font,
  * for code points modified by variation selectors. For variation-selector
  * support, user hb_font_get_variation_glyph() or use hb_font_get_glyph().
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 1.2.3
  **/
@@ -1026,7 +1026,7 @@ hb_font_get_nominal_glyphs (hb_font_t *font,
  * by the specified variation-selector code point, in the specified
  * font.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 1.2.3
  **/
@@ -1136,7 +1136,7 @@ hb_font_get_glyph_v_advances (hb_font_t*            font,
  * Fetches the (X,Y) coordinates of the origin for a glyph ID
  * in the specified font, for horizontal text segments.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1159,7 +1159,7 @@ hb_font_get_glyph_h_origin (hb_font_t      *font,
  * Fetches the (X,Y) coordinates of the origin for a glyph ID
  * in the specified font, for vertical text segments.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1232,7 +1232,7 @@ hb_font_get_glyph_v_kerning (hb_font_t      *font,
  * Fetches the #hb_glyph_extents_t data for a glyph ID
  * in the specified font.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1255,7 +1255,7 @@ hb_font_get_glyph_extents (hb_font_t          *font,
  * Fetches the (x,y) coordinates of a specified contour-point index
  * in the specified glyph, within the specified font.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1278,7 +1278,7 @@ hb_font_get_glyph_contour_point (hb_font_t      *font,
  *
  * Fetches the glyph-name string for a glyph ID in the specified @font.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1302,7 +1302,7 @@ hb_font_get_glyph_name (hb_font_t      *font,
  *
  * <note>Note: @len == -1 means the name string is null-terminated.</note>
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1537,7 +1537,7 @@ hb_font_get_glyph_kerning_for_direction (hb_font_t      *font,
  * Calls the appropriate direction-specific variant (horizontal
  * or vertical) depending on the value of @direction.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1566,7 +1566,7 @@ hb_font_get_glyph_extents_for_origin (hb_font_t          *font,
  * Calls the appropriate direction-specific variant (horizontal
  * or vertical) depending on the value of @direction.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1617,7 +1617,7 @@ hb_font_glyph_to_string (hb_font_t      *font,
  *
  * <note>Note: @len == -1 means the string is null-terminated.</note>
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1866,7 +1866,7 @@ hb_font_destroy (hb_font_t *font)
  *
  * Attaches a user-data key/data pair to the specified font object.
  *
- * Return value: %true if success, %false otherwise
+ * Return value: `true` if success, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -1928,7 +1928,7 @@ hb_font_make_immutable (hb_font_t *font)
  *
  * Tests whether a font object is immutable.
  *
- * Return value: %true if @font is immutable, %false otherwise
+ * Return value: `true` if @font is immutable, `false` otherwise
  *
  * Since: 0.9.2
  **/
diff --git a/src/hb-font.h b/src/hb-font.h
index ca6ecf796..3f27bca28 100644
--- a/src/hb-font.h
+++ b/src/hb-font.h
@@ -198,7 +198,7 @@ typedef hb_font_get_font_extents_func_t hb_font_get_font_v_extents_func_t;
  * This method should retrieve the nominal glyph ID for a specified Unicode code
  * point. Glyph IDs must be returned in a #hb_codepoint_t output parameter.
  * 
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  **/
 typedef hb_bool_t (*hb_font_get_nominal_glyph_func_t) (hb_font_t *font, void *font_data,
@@ -221,7 +221,7 @@ typedef hb_bool_t (*hb_font_get_nominal_glyph_func_t) (hb_font_t *font, void *fo
  * followed by a specified Variation Selector code point. Glyph IDs must be
  * returned in a #hb_codepoint_t output parameter.
  * 
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  **/
 typedef hb_bool_t (*hb_font_get_variation_glyph_func_t) (hb_font_t *font, void *font_data,
@@ -362,7 +362,7 @@ typedef hb_font_get_glyph_advances_func_t hb_font_get_glyph_v_advances_func_t;
  * origin for a glyph. Each coordinate must be returned in an #hb_position_t
  * output parameter.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  * 
  **/
 typedef hb_bool_t (*hb_font_get_glyph_origin_func_t) (hb_font_t *font, void *font_data,
@@ -434,7 +434,7 @@ typedef hb_font_get_glyph_kerning_func_t hb_font_get_glyph_h_kerning_func_t;
  * This method should retrieve the extents for a specified glyph. Extents must be 
  * returned in an #hb_glyph_extents output parameter.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  * 
  **/
 typedef hb_bool_t (*hb_font_get_glyph_extents_func_t) (hb_font_t *font, void *font_data,
@@ -458,7 +458,7 @@ typedef hb_bool_t (*hb_font_get_glyph_extents_func_t) (hb_font_t *font, void *fo
  * specified contour point in a glyph. Each coordinate must be returned as
  * an #hb_position_t output parameter.
  * 
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  **/
 typedef hb_bool_t (*hb_font_get_glyph_contour_point_func_t) (hb_font_t *font, void *font_data,
@@ -481,7 +481,7 @@ typedef hb_bool_t (*hb_font_get_glyph_contour_point_func_t) (hb_font_t *font, vo
  * This method should retrieve the glyph name that corresponds to a
  * glyph ID. The name should be returned in a string output parameter.
  * 
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  **/
 typedef hb_bool_t (*hb_font_get_glyph_name_func_t) (hb_font_t *font, void *font_data,
@@ -503,7 +503,7 @@ typedef hb_bool_t (*hb_font_get_glyph_name_func_t) (hb_font_t *font, void *font_
  * This method should retrieve the glyph ID that corresponds to a glyph-name
  * string. 
  * 
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  **/
 typedef hb_bool_t (*hb_font_get_glyph_from_name_func_t) (hb_font_t *font, void *font_data,
diff --git a/src/hb-ft.cc b/src/hb-ft.cc
index b526a8286..e0a7f1a5e 100644
--- a/src/hb-ft.cc
+++ b/src/hb-ft.cc
@@ -241,7 +241,7 @@ hb_ft_font_get_load_flags (hb_font_t *font)
  * Fetches the FT_Face associated with the specified #hb_font_t
  * font object.
  *
- * Return value: (nullable): the FT_Face found or %NULL
+ * Return value: (nullable): the FT_Face found or `NULL`
  *
  * Since: 0.9.2
  **/
@@ -263,7 +263,7 @@ hb_ft_font_get_face (hb_font_t *font)
  * Gets the FT_Face associated with @font, This face will be kept around until
  * you call hb_ft_font_unlock_face().
  *
- * Return value: (nullable): the FT_Face associated with @font or %NULL
+ * Return value: (nullable): the FT_Face associated with @font or `NULL`
  * Since: 2.6.5
  **/
 FT_Face
diff --git a/src/hb-graphite2.cc b/src/hb-graphite2.cc
index 63dc18b46..15d6ce80b 100644
--- a/src/hb-graphite2.cc
+++ b/src/hb-graphite2.cc
@@ -198,7 +198,7 @@ _hb_graphite2_shaper_font_data_destroy (hb_graphite2_font_data_t *data HB_UNUSED
  * hb_graphite2_font_get_gr_font:
  * @font: An #hb_font_t
  *
- * Always returns %NULL. Use hb_graphite2_face_get_gr_face() instead.
+ * Always returns `NULL`. Use hb_graphite2_face_get_gr_face() instead.
  *
  * Return value: (nullable): Graphite2 font associated with @font.
  *
diff --git a/src/hb-map.cc b/src/hb-map.cc
index 089615c72..a4b549a45 100644
--- a/src/hb-map.cc
+++ b/src/hb-map.cc
@@ -122,7 +122,7 @@ hb_map_destroy (hb_map_t *map)
  *
  * Attaches a user-data key/data pair to the specified map.
  *
- * Return value: %true if success, %false otherwise
+ * Return value: `true` if success, `false` otherwise
  *
  * Since: 1.7.7
  **/
@@ -162,7 +162,7 @@ hb_map_get_user_data (hb_map_t           *map,
  *
  * Tests whether memory allocation for a set was successful.
  *
- * Return value: %true if allocation succeeded, %false otherwise
+ * Return value: `true` if allocation succeeded, `false` otherwise
  *
  * Since: 1.7.7
  **/
@@ -251,7 +251,7 @@ hb_map_del (hb_map_t       *map,
  *
  * Tests whether @key is an element of @map.
  *
- * Return value: %true if @key is found in @map, %false otherwise
+ * Return value: `true` if @key is found in @map, `false` otherwise
  *
  * Since: 1.7.7
  **/
@@ -283,7 +283,7 @@ hb_map_clear (hb_map_t *map)
  *
  * Tests whether @map is empty (contains no elements).
  *
- * Return value: %true if @map is empty
+ * Return value: `true` if @map is empty
  *
  * Since: 1.7.7
  **/
@@ -317,7 +317,7 @@ hb_map_get_population (const hb_map_t *map)
  * Tests whether @map and @other are equal (contain the same
  * elements).
  *
- * Return value: %true if the two maps are equal, %false otherwise.
+ * Return value: `true` if the two maps are equal, `false` otherwise.
  *
  * Since: 4.3.0
  **/
diff --git a/src/hb-ot-color.cc b/src/hb-ot-color.cc
index 16077765b..a9ae01368 100644
--- a/src/hb-ot-color.cc
+++ b/src/hb-ot-color.cc
@@ -61,7 +61,7 @@
  *
  * Tests whether a face includes a `CPAL` color-palette table.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 2.1.0
  */
@@ -192,7 +192,7 @@ hb_ot_color_palette_get_colors (hb_face_t     *face,
  *
  * Tests whether a face includes any `COLR` color layers.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 2.1.0
  */
@@ -239,7 +239,7 @@ hb_ot_color_glyph_get_layers (hb_face_t           *face,
  *
  * Tests whether a face includes any `SVG` glyph images.
  *
- * Return value: %true if data found, %false otherwise.
+ * Return value: `true` if data found, `false` otherwise.
  *
  * Since: 2.1.0
  */
@@ -279,7 +279,7 @@ hb_ot_color_glyph_reference_svg (hb_face_t *face, hb_codepoint_t glyph)
  *
  * Tests whether a face has PNG glyph images (either in `CBDT` or `sbix` tables).
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 2.1.0
  */
diff --git a/src/hb-ot-layout.cc b/src/hb-ot-layout.cc
index 142c843da..cefdf1b96 100644
--- a/src/hb-ot-layout.cc
+++ b/src/hb-ot-layout.cc
@@ -79,7 +79,7 @@ using OT::Layout::GPOS;
  * Tests whether a face includes any kerning data in the 'kern' table.
  * Does NOT test for kerning lookups in the GPOS table.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  **/
 bool
@@ -95,7 +95,7 @@ hb_ot_layout_has_kerning (hb_face_t *face)
  * Tests whether a face includes any state-machine kerning in the 'kern' table.
  * Does NOT examine the GPOS table.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  **/
 bool
@@ -115,7 +115,7 @@ hb_ot_layout_has_machine_kerning (hb_face_t *face)
  *
  * Does NOT examine the GPOS table.
  *
- * Return value: %true is data found, %false otherwise
+ * Return value: `true` is data found, `false` otherwise
  *
  **/
 bool
@@ -272,7 +272,7 @@ _hb_ot_layout_set_glyph_props (hb_font_t *font,
  *
  * Tests whether a face has any glyph classes defined in its GDEF table.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  **/
 hb_bool_t
@@ -461,7 +461,7 @@ hb_ot_layout_table_get_script_tags (hb_face_t    *face,
  * Fetches the index if a given script tag in the specified face's GSUB table
  * or GPOS table.
  *
- * Return value: %true if the script is found, %false otherwise
+ * Return value: `true` if the script is found, `false` otherwise
  *
  **/
 hb_bool_t
@@ -535,7 +535,7 @@ hb_ot_layout_table_choose_script (hb_face_t      *face,
  * #HB_OT_LAYOUT_NO_SCRIPT_INDEX.
  *
  * Return value:
- * %true if one of the requested scripts is selected, %false if a fallback
+ * `true` if one of the requested scripts is selected, `false` if a fallback
  * script is selected or if no scripts are selected.
  *
  * Since: 2.0.0
@@ -628,7 +628,7 @@ hb_ot_layout_table_get_feature_tags (hb_face_t    *face,
  * Fetches the index for a given feature tag in the specified face's GSUB table
  * or GPOS table.
  *
- * Return value: %true if the feature is found, %false otherwise
+ * Return value: `true` if the feature is found, `false` otherwise
  **/
 bool
 hb_ot_layout_table_find_feature (hb_face_t    *face,
@@ -695,7 +695,7 @@ hb_ot_layout_script_get_language_tags (hb_face_t    *face,
  * Fetches the index of a given language tag in the specified face's GSUB table
  * or GPOS table, underneath the specified script tag.
  *
- * Return value: %true if the language tag is found, %false otherwise
+ * Return value: `true` if the language tag is found, `false` otherwise
  *
  * Since: 0.6.0
  * Deprecated: 2.0.0
@@ -730,10 +730,10 @@ hb_ot_layout_script_find_language (hb_face_t    *face,
  * in the specified face's GSUB or GPOS table, underneath the specified script
  * index.
  *
- * If none of the given language tags is found, %false is returned and
+ * If none of the given language tags is found, `false` is returned and
  * @language_index is set to the default language index.
  *
- * Return value: %true if one of the given language tags is found, %false otherwise
+ * Return value: `true` if one of the given language tags is found, `false` otherwise
  *
  * Since: 2.0.0
  **/
@@ -776,7 +776,7 @@ hb_ot_layout_script_select_language (hb_face_t      *face,
  * Fetches the index of a requested feature in the given face's GSUB or GPOS table,
  * underneath the specified script and language.
  *
- * Return value: %true if the feature is found, %false otherwise
+ * Return value: `true` if the feature is found, `false` otherwise
  *
  **/
 hb_bool_t
@@ -807,7 +807,7 @@ hb_ot_layout_language_get_required_feature_index (hb_face_t    *face,
  * Fetches the tag of a requested feature index in the given face's GSUB or GPOS table,
  * underneath the specified script and language.
  *
- * Return value: %true if the feature is found, %false otherwise
+ * Return value: `true` if the feature is found, `false` otherwise
  *
  * Since: 0.9.30
  **/
@@ -917,7 +917,7 @@ hb_ot_layout_language_get_feature_tags (hb_face_t    *face,
  * Fetches the index of a given feature tag in the specified face's GSUB table
  * or GPOS table, underneath the specified script and language.
  *
- * Return value: %true if the feature is found, %false otherwise
+ * Return value: `true` if the feature is found, `false` otherwise
  *
  **/
 hb_bool_t
@@ -1314,7 +1314,7 @@ hb_ot_layout_lookup_collect_glyphs (hb_face_t    *face,
  * Fetches a list of feature variations in the specified face's GSUB table
  * or GPOS table, at the specified variation coordinates.
  *
- * Return value: %true if feature variations were found, %false otherwise.
+ * Return value: `true` if feature variations were found, `false` otherwise.
  *
  **/
 hb_bool_t
@@ -1377,7 +1377,7 @@ hb_ot_layout_feature_with_variations_get_lookups (hb_face_t    *face,
  *
  * Tests whether the specified face includes any GSUB substitutions.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  **/
 hb_bool_t
@@ -1399,7 +1399,7 @@ hb_ot_layout_has_substitution (hb_face_t *face)
  * Tests whether a specified lookup in the specified face would
  * trigger a substitution on the given glyph sequence.
  *
- * Return value: %true if a substitution would be triggered, %false otherwise
+ * Return value: `true` if a substitution would be triggered, `false` otherwise
  *
  * Since: 0.9.7
  **/
@@ -1561,7 +1561,7 @@ hb_ot_layout_lookups_substitute_closure (hb_face_t      *face,
  *
  * Tests whether the specified face includes any GPOS positioning.
  *
- * Return value: %true if the face has GPOS data, %false otherwise
+ * Return value: `true` if the face has GPOS data, `false` otherwise
  *
  **/
 hb_bool_t
@@ -1634,7 +1634,7 @@ hb_ot_layout_position_finish_offsets (hb_font_t *font, hb_buffer_t *buffer)
  * For more information on this distinction, see the [`size` feature documentation](
  * https://docs.microsoft.com/en-us/typography/opentype/spec/features_pt#tag-size).
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 0.9.10
  **/
@@ -1698,7 +1698,7 @@ hb_ot_layout_get_size_params (hb_face_t       *face,
  * Fetches name indices from feature parameters for "Stylistic Set" ('ssXX') or
  * "Character Variant" ('cvXX') features.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 2.0.0
  **/
@@ -2051,7 +2051,7 @@ hb_ot_layout_get_horizontal_baseline_tag_for_script (hb_script_t script)
  *
  * Fetches a baseline value from the face.
  *
- * Return value: %true if found baseline value in the font.
+ * Return value: `true` if found baseline value in the font.
  *
  * Since: 2.6.0
  **/
diff --git a/src/hb-ot-math.cc b/src/hb-ot-math.cc
index f44ac3584..c515867bd 100644
--- a/src/hb-ot-math.cc
+++ b/src/hb-ot-math.cc
@@ -56,7 +56,7 @@
  *
  * Tests whether a face has a `MATH` table.
  *
- * Return value: %true if the table is found, %false otherwise
+ * Return value: `true` if the table is found, `false` otherwise
  *
  * Since: 1.3.3
  **/
@@ -142,7 +142,7 @@ hb_ot_math_get_glyph_top_accent_attachment (hb_font_t *font,
  *
  * Tests whether the given glyph index is an extended shape in the face.
  *
- * Return value: %true if the glyph is an extended shape, %false otherwise
+ * Return value: `true` if the glyph is an extended shape, `false` otherwise
  *
  * Since: 1.3.3
  **/
diff --git a/src/hb-ot-var.cc b/src/hb-ot-var.cc
index 0376e26b4..f000f2726 100644
--- a/src/hb-ot-var.cc
+++ b/src/hb-ot-var.cc
@@ -56,7 +56,7 @@
  *
  * Tests whether a face includes any OpenType variation data in the `fvar` table.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 1.4.2
  **/
@@ -162,7 +162,7 @@ hb_ot_var_get_axis_infos (hb_face_t             *face,
  * Fetches the variation-axis information corresponding to the specified axis tag
  * in the specified face.
  *
- * Return value: %true if data found, %false otherwise
+ * Return value: `true` if data found, `false` otherwise
  *
  * Since: 2.2.0
  **/
diff --git a/src/hb-set.cc b/src/hb-set.cc
index 2d458294f..b3de01a8b 100644
--- a/src/hb-set.cc
+++ b/src/hb-set.cc
@@ -122,7 +122,7 @@ hb_set_destroy (hb_set_t *set)
  *
  * Attaches a user-data key/data pair to the specified set.
  *
- * Return value: %true if success, %false otherwise
+ * Return value: `true` if success, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -162,7 +162,7 @@ hb_set_get_user_data (hb_set_t           *set,
  *
  * Tests whether memory allocation for a set was successful.
  *
- * Return value: %true if allocation succeeded, %false otherwise
+ * Return value: `true` if allocation succeeded, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -212,7 +212,7 @@ hb_set_clear (hb_set_t *set)
  *
  * Tests whether a set is empty (contains no elements).
  *
- * Return value: %true if @set is empty
+ * Return value: `true` if @set is empty
  *
  * Since: 0.9.7
  **/
@@ -229,7 +229,7 @@ hb_set_is_empty (const hb_set_t *set)
  *
  * Tests whether @codepoint belongs to @set.
  *
- * Return value: %true if @codepoint is in @set, %false otherwise
+ * Return value: `true` if @codepoint is in @set, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -348,7 +348,7 @@ hb_set_del_range (hb_set_t       *set,
  * Tests whether @set and @other are equal (contain the same
  * elements).
  *
- * Return value: %true if the two sets are equal, %false otherwise.
+ * Return value: `true` if the two sets are equal, `false` otherwise.
  *
  * Since: 0.9.7
  **/
@@ -383,7 +383,7 @@ hb_set_hash (const hb_set_t *set)
  *
  * Tests whether @set is a subset of @larger_set.
  *
- * Return value: %true if the @set is a subset of (or equal to) @larger_set, %false otherwise.
+ * Return value: `true` if the @set is a subset of (or equal to) @larger_set, `false` otherwise.
  *
  * Since: 1.8.1
  **/
@@ -553,7 +553,7 @@ hb_set_get_max (const hb_set_t *set)
  *
  * Set @codepoint to #HB_SET_VALUE_INVALID to get started.
  *
- * Return value: %true if there was a next value, %false otherwise
+ * Return value: `true` if there was a next value, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -574,7 +574,7 @@ hb_set_next (const hb_set_t *set,
  *
  * Set @codepoint to #HB_SET_VALUE_INVALID to get started.
  *
- * Return value: %true if there was a previous value, %false otherwise
+ * Return value: `true` if there was a previous value, `false` otherwise
  *
  * Since: 1.8.0
  **/
@@ -597,7 +597,7 @@ hb_set_previous (const hb_set_t *set,
  *
  * Set @last to #HB_SET_VALUE_INVALID to get started.
  *
- * Return value: %true if there was a next range, %false otherwise
+ * Return value: `true` if there was a next range, `false` otherwise
  *
  * Since: 0.9.7
  **/
@@ -621,7 +621,7 @@ hb_set_next_range (const hb_set_t *set,
  *
  * Set @first to #HB_SET_VALUE_INVALID to get started.
  *
- * Return value: %true if there was a previous range, %false otherwise
+ * Return value: `true` if there was a previous range, `false` otherwise
  *
  * Since: 1.8.0
  **/
diff --git a/src/hb-shape-plan.cc b/src/hb-shape-plan.cc
index 0af07825f..f97aaed11 100644
--- a/src/hb-shape-plan.cc
+++ b/src/hb-shape-plan.cc
@@ -335,7 +335,7 @@ hb_shape_plan_destroy (hb_shape_plan_t *shape_plan)
  *
  * Attaches a user-data key/data pair to the given shaping plan. 
  *
- * Return value: %true if success, %false otherwise.
+ * Return value: `true` if success, `false` otherwise.
  *
  * Since: 0.9.7
  **/
@@ -440,7 +440,7 @@ _hb_shape_plan_execute_internal (hb_shape_plan_t    *shape_plan,
  * Executes the given shaping plan on the specified buffer, using
  * the given @font and @features.
  *
- * Return value: %true if success, %false otherwise.
+ * Return value: `true` if success, `false` otherwise.
  *
  * Since: 0.9.7
  **/
diff --git a/src/hb-shape.cc b/src/hb-shape.cc
index 14ec92828..547d0afc4 100644
--- a/src/hb-shape.cc
+++ b/src/hb-shape.cc
@@ -106,12 +106,12 @@ hb_shape_list_shapers ()
  * @font: an #hb_font_t to use for shaping
  * @buffer: an #hb_buffer_t to shape
  * @features: (array length=num_features) (nullable): an array of user
- *    specified #hb_feature_t or %NULL
+ *    specified #hb_feature_t or `NULL`
  * @num_features: the length of @features array
- * @shaper_list: (array zero-terminated=1) (nullable): a %NULL-terminated
- *    array of shapers to use or %NULL
+ * @shaper_list: (array zero-terminated=1) (nullable): a `NULL`-terminated
+ *    array of shapers to use or `NULL`
  *
- * See hb_shape() for details. If @shaper_list is not %NULL, the specified
+ * See hb_shape() for details. If @shaper_list is not `NULL`, the specified
  * shapers will be used in the given order, otherwise the default shapers list
  * will be used.
  *
@@ -173,11 +173,11 @@ hb_shape_full (hb_font_t          *font,
  * @font: an #hb_font_t to use for shaping
  * @buffer: an #hb_buffer_t to shape
  * @features: (array length=num_features) (nullable): an array of user
- *    specified #hb_feature_t or %NULL
+ *    specified #hb_feature_t or `NULL`
  * @num_features: the length of @features array
  *
  * Shapes @buffer using @font turning its Unicode characters content to
- * positioned glyphs. If @features is not %NULL, it will be used to control the
+ * positioned glyphs. If @features is not `NULL`, it will be used to control the
  * features applied during shaping. If two @features have the same tag but
  * overlapping ranges the value of the feature with the higher index takes
  * precedence.
diff --git a/src/hb-subset-input.cc b/src/hb-subset-input.cc
index 028ddf903..e254f8cd4 100644
--- a/src/hb-subset-input.cc
+++ b/src/hb-subset-input.cc
@@ -32,7 +32,7 @@
  *
  * Creates a new subset input object.
  *
- * Return value: (transfer full): New subset input, or %NULL if failed. Destroy
+ * Return value: (transfer full): New subset input, or `NULL` if failed. Destroy
  * with hb_subset_input_destroy().
  *
  * Since: 1.8.0
@@ -342,7 +342,7 @@ hb_subset_input_set_flags (hb_subset_input_t *input,
  *
  * Attaches a user-data key/data pair to the given subset input object.
  *
- * Return value: %true if success, %false otherwise
+ * Return value: `true` if success, `false` otherwise
  *
  * Since: 2.9.0
  **/
diff --git a/src/hb-subset-plan.cc b/src/hb-subset-plan.cc
index 4e3bb1d47..c15a3664b 100644
--- a/src/hb-subset-plan.cc
+++ b/src/hb-subset-plan.cc
@@ -755,7 +755,7 @@ hb_subset_plan_reference (hb_subset_plan_t *plan)
  *
  * Attaches a user-data key/data pair to the given subset plan object.
  *
- * Return value: %true if success, %false otherwise
+ * Return value: `true` if success, `false` otherwise
  *
  * Since: 4.0.0
  **/
diff --git a/src/hb-unicode.cc b/src/hb-unicode.cc
index 05f74b923..9899e01a4 100644
--- a/src/hb-unicode.cc
+++ b/src/hb-unicode.cc
@@ -281,7 +281,7 @@ hb_unicode_funcs_destroy (hb_unicode_funcs_t *ufuncs)
  *
  * Attaches a user-data key/data pair to the specified Unicode-functions structure. 
  *
- * Return value: %true if success, %false otherwise
+ * Return value: `true` if success, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -340,7 +340,7 @@ hb_unicode_funcs_make_immutable (hb_unicode_funcs_t *ufuncs)
  * Tests whether the specified Unicode-functions structure
  * is immutable.
  *
- * Return value: %true if @ufuncs is immutable, %false otherwise
+ * Return value: `true` if @ufuncs is immutable, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -421,7 +421,7 @@ HB_UNICODE_FUNCS_IMPLEMENT_CALLBACKS_SIMPLE
  * Calls the composition function of the specified
  * Unicode-functions structure @ufuncs.
  *
- * Return value: %true if @a and @b composed, %false otherwise
+ * Return value: `true` if @a and @b composed, `false` otherwise
  *
  * Since: 0.9.2
  **/
@@ -446,7 +446,7 @@ hb_unicode_compose (hb_unicode_funcs_t *ufuncs,
  * Calls the decomposition function of the specified
  * Unicode-functions structure @ufuncs.
  *
- * Return value: %true if @ab was decomposed, %false otherwise
+ * Return value: `true` if @ab was decomposed, `false` otherwise
  *
  * Since: 0.9.2
  **/
diff --git a/src/hb-unicode.h b/src/hb-unicode.h
index c04ee15a0..a50038457 100644
--- a/src/hb-unicode.h
+++ b/src/hb-unicode.h
@@ -429,7 +429,7 @@ typedef hb_script_t			(*hb_unicode_script_func_t)		(hb_unicode_funcs_t *ufuncs,
  * The method must return an #hb_bool_t indicating the success
  * of the composition.
  * 
- * Return value: %true is @a,@b composed, %false otherwise
+ * Return value: `true` is @a,@b composed, `false` otherwise
  *
  **/
 typedef hb_bool_t			(*hb_unicode_compose_func_t)		(hb_unicode_funcs_t *ufuncs,
@@ -453,7 +453,7 @@ typedef hb_bool_t			(*hb_unicode_compose_func_t)		(hb_unicode_funcs_t *ufuncs,
  * output parameters (if successful). The method must return an
  * #hb_bool_t indicating the success of the composition.
  * 
- * Return value: %true if @ab decomposed, %false otherwise
+ * Return value: `true` if @ab decomposed, `false` otherwise
  *
  **/
 typedef hb_bool_t			(*hb_unicode_decompose_func_t)		(hb_unicode_funcs_t *ufuncs,