diff --git a/src/hb-ot-layout-gsub-private.h b/src/hb-ot-layout-gsub-private.h
index 9f0b0d8dd..1db04a9bf 100644
--- a/src/hb-ot-layout-gsub-private.h
+++ b/src/hb-ot-layout-gsub-private.h
@@ -254,10 +254,10 @@ struct AlternateSubstFormat1 {
     unsigned int alt_index = 0;
 
     /* XXX callback to user to choose alternate
-    if ( gsub->altfunc )
-      alt_index = (gsub->altfunc)( buffer->out_pos, glyph_id,
-				   aset.GlyphCount, aset.Alternate,
-				   gsub->data );
+    if (layout->altfunc)
+      alt_index = (layout->altfunc)(layout, buffer,
+				    buffer->out_pos, glyph_id,
+				    alt_set.len, alt_set.array);
 				   */
 
     if (HB_UNLIKELY (alt_index >= alt_set.len))
@@ -370,7 +370,7 @@ struct Ligature {
 	(buffer->in_pos)++;
       }
 
-      /* XXX We  should possibly reassign lig_id and component for any
+      /* TODO We should possibly reassign lig_id and component for any
        * components of a previous ligature that s now being removed as part of
        * this ligature. */
     }
@@ -773,7 +773,7 @@ ASSERT_SIZE (GSUB, 10);
 inline bool ExtensionSubstFormat1::substitute (LOOKUP_ARGS_DEF) const {
   unsigned int lookup_type = get_type ();
 
-  /* TODO: belongs to sanitize() */
+  /* TODO belongs to sanitize() */
   if (HB_UNLIKELY (lookup_type == GSUB_ReverseChainSingle))
     return false;
 
diff --git a/src/hb-ot-layout-open-private.h b/src/hb-ot-layout-open-private.h
index 31d083a83..0dd291aa9 100644
--- a/src/hb-ot-layout-open-private.h
+++ b/src/hb-ot-layout-open-private.h
@@ -203,7 +203,7 @@ struct Null <Type> { \
  * Int types
  */
 
-/* XXX define these as structs of chars on machines that do not allow
+/* TODO define these as structs of chars on machines that do not allow
  * unaligned access (using templates?). */
 #define DEFINE_INT_TYPE1(NAME, TYPE, BIG_ENDIAN) \
   inline NAME& operator = (TYPE i) { v = BIG_ENDIAN(i); return *this; } \
diff --git a/src/hb-ot-layout.cc b/src/hb-ot-layout.cc
index 367cb59fc..2e18a0516 100644
--- a/src/hb-ot-layout.cc
+++ b/src/hb-ot-layout.cc
@@ -85,7 +85,7 @@ hb_ot_layout_destroy (hb_ot_layout_t *layout)
  * GDEF
  */
 
-/* XXX the public class_t is a mess */
+/* TODO the public class_t is a mess */
 
 hb_bool_t
 hb_ot_layout_has_font_glyph_classes (hb_ot_layout_t *layout)
@@ -532,7 +532,7 @@ hb_ot_layout_substitute_lookup (hb_ot_layout_t              *layout,
 
 
 
-/* XXX dupped, until he old code can be removed */
+/* TODO dupped, until he old code can be removed */
 
 static HB_Error
 hb_buffer_duplicate_out_buffer( HB_Buffer buffer )