diff --git a/src/gen-vowel-constraints.py b/src/gen-vowel-constraints.py
index 55a9ecf86..2e9b50bad 100755
--- a/src/gen-vowel-constraints.py
+++ b/src/gen-vowel-constraints.py
@@ -171,8 +171,8 @@ print ()
 print ('static void')
 print ('_output_dotted_circle (hb_buffer_t *buffer)')
 print ('{')
-print ('  hb_glyph_info_t &dottedcircle = buffer->output_glyph (0x25CCu);')
-print ('  _hb_glyph_info_reset_continuation (&dottedcircle);')
+print ('  (void) buffer->output_glyph (0x25CCu);')
+print ('  _hb_glyph_info_reset_continuation (&buffer->prev());')
 print ('}')
 print ()
 print ('static void')
diff --git a/src/hb-aat-layout-morx-table.hh b/src/hb-aat-layout-morx-table.hh
index b9fabe2b1..e3bc268d2 100644
--- a/src/hb-aat-layout-morx-table.hh
+++ b/src/hb-aat-layout-morx-table.hh
@@ -738,8 +738,7 @@ struct InsertionSubtable
 	if (buffer->idx < buffer->len && !before)
 	  if (unlikely (!buffer->copy_glyph ())) return;
 	/* TODO We ignore KashidaLike setting. */
-	for (unsigned int i = 0; i < count; i++)
-	  buffer->output_glyph (glyphs[i]);
+	if (unlikely (!buffer->replace_glyphs (0, count, glyphs))) return;
 	if (buffer->idx < buffer->len && !before)
 	  buffer->skip_glyph ();
 
@@ -766,8 +765,7 @@ struct InsertionSubtable
 	if (buffer->idx < buffer->len && !before)
 	  if (unlikely (!buffer->copy_glyph ())) return;
 	/* TODO We ignore KashidaLike setting. */
-	for (unsigned int i = 0; i < count; i++)
-	  buffer->output_glyph (glyphs[i]);
+	if (unlikely (!buffer->replace_glyphs (0, count, glyphs))) return;
 	if (buffer->idx < buffer->len && !before)
 	  buffer->skip_glyph ();
 
diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index 494bf395e..8cad6ab8e 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -342,33 +342,6 @@ hb_buffer_t::swap_buffers ()
   idx = 0;
 }
 
-
-bool
-hb_buffer_t::replace_glyphs (unsigned int num_in,
-			     unsigned int num_out,
-			     const uint32_t *glyph_data)
-{
-  if (unlikely (!make_room_for (num_in, num_out))) return false;
-
-  assert (idx + num_in <= len);
-
-  merge_clusters (idx, idx + num_in);
-
-  hb_glyph_info_t orig_info = info[idx];
-  hb_glyph_info_t *pinfo = &out_info[out_len];
-  for (unsigned int i = 0; i < num_out; i++)
-  {
-    *pinfo = orig_info;
-    pinfo->codepoint = glyph_data[i];
-    pinfo++;
-  }
-
-  idx  += num_in;
-  out_len += num_out;
-
-  return true;
-}
-
 bool
 hb_buffer_t::move_to (unsigned int i)
 {
diff --git a/src/hb-buffer.hh b/src/hb-buffer.hh
index 97c5a0279..c457e7392 100644
--- a/src/hb-buffer.hh
+++ b/src/hb-buffer.hh
@@ -210,10 +210,31 @@ struct hb_buffer_t
   HB_INTERNAL void clear_output ();
   HB_INTERNAL void clear_positions ();
 
-  HB_INTERNAL HB_NODISCARD
-  bool replace_glyphs (unsigned int num_in,
-		       unsigned int num_out,
-		       const hb_codepoint_t *glyph_data);
+  template <typename T>
+  HB_NODISCARD bool replace_glyphs (unsigned int num_in,
+				    unsigned int num_out,
+				    const T *glyph_data)
+  {
+    if (unlikely (!make_room_for (num_in, num_out))) return false;
+
+    assert (idx + num_in <= len);
+
+    merge_clusters (idx, idx + num_in);
+
+    hb_glyph_info_t &orig_info = idx < len ? cur() : prev();
+
+    hb_glyph_info_t *pinfo = &out_info[out_len];
+    for (unsigned int i = 0; i < num_out; i++)
+    {
+      *pinfo = orig_info;
+      pinfo->codepoint = glyph_data[i];
+      pinfo++;
+    }
+
+    idx  += num_in;
+    out_len += num_out;
+    return true;
+  }
 
   HB_NODISCARD bool replace_glyph (hb_codepoint_t glyph_index)
   {
@@ -229,18 +250,15 @@ struct hb_buffer_t
     return true;
   }
   /* Makes a copy of the glyph at idx to output and replace glyph_index */
-  hb_glyph_info_t & output_glyph (hb_codepoint_t glyph_index)
+  HB_NODISCARD bool output_glyph (hb_codepoint_t glyph_index)
   {
-    if (unlikely (!make_room_for (0, 1))) return Crap (hb_glyph_info_t);
+    if (unlikely (!make_room_for (0, 1))) return false;
 
-    if (unlikely (idx == len && !out_len))
-      return Crap (hb_glyph_info_t);
-
-    out_info[out_len] = idx < len ? info[idx] : out_info[out_len - 1];
+    out_info[out_len] = idx < len ? cur() : prev();
     out_info[out_len].codepoint = glyph_index;
 
     out_len++;
-    return out_info[out_len - 1];
+    return true;
   }
   HB_NODISCARD bool output_info (const hb_glyph_info_t &glyph_info)
   {
diff --git a/src/hb-ot-layout-gsubgpos.hh b/src/hb-ot-layout-gsubgpos.hh
index bfc58624f..b93b73c04 100644
--- a/src/hb-ot-layout-gsubgpos.hh
+++ b/src/hb-ot-layout-gsubgpos.hh
@@ -676,7 +676,7 @@ struct hb_ot_apply_context_t :
 				   unsigned int class_guess) const
   {
     _set_glyph_props (glyph_index, class_guess, false, true);
-    buffer->output_glyph (glyph_index);
+    (void) buffer->output_glyph (glyph_index);
   }
 };
 
diff --git a/src/hb-ot-shape-complex-thai.cc b/src/hb-ot-shape-complex-thai.cc
index 9159c9f36..925e28d3b 100644
--- a/src/hb-ot-shape-complex-thai.cc
+++ b/src/hb-ot-shape-complex-thai.cc
@@ -332,10 +332,9 @@ preprocess_text_thai (const hb_ot_shape_plan_t *plan,
     }
 
     /* Is SARA AM. Decompose and reorder. */
-    hb_glyph_info_t &nikhahit = buffer->output_glyph (NIKHAHIT_FROM_SARA_AM (u));
-    _hb_glyph_info_set_continuation (&nikhahit);
-    if (unlikely (!buffer->replace_glyph (SARA_AA_FROM_SARA_AM (u))))
-      break;
+    if (unlikely (!buffer->output_glyph (NIKHAHIT_FROM_SARA_AM (u)))) break;
+    _hb_glyph_info_set_continuation (&buffer->prev());
+    if (unlikely (!buffer->replace_glyph (SARA_AA_FROM_SARA_AM (u)))) break;
 
     /* Make Nikhahit be recognized as a ccc=0 mark when zeroing widths. */
     unsigned int end = buffer->out_len;
diff --git a/src/hb-ot-shape-complex-vowel-constraints.cc b/src/hb-ot-shape-complex-vowel-constraints.cc
index 124716eb6..2c61e976f 100644
--- a/src/hb-ot-shape-complex-vowel-constraints.cc
+++ b/src/hb-ot-shape-complex-vowel-constraints.cc
@@ -23,8 +23,8 @@
 static void
 _output_dotted_circle (hb_buffer_t *buffer)
 {
-  hb_glyph_info_t &dottedcircle = buffer->output_glyph (0x25CCu);
-  _hb_glyph_info_reset_continuation (&dottedcircle);
+  (void) buffer->output_glyph (0x25CCu);
+  _hb_glyph_info_reset_continuation (&buffer->prev());
 }
 
 static void
diff --git a/src/hb-ot-shape-normalize.cc b/src/hb-ot-shape-normalize.cc
index bce9dcf5d..8ad2d771a 100644
--- a/src/hb-ot-shape-normalize.cc
+++ b/src/hb-ot-shape-normalize.cc
@@ -101,8 +101,9 @@ set_glyph (hb_glyph_info_t &info, hb_font_t *font)
 static inline void
 output_char (hb_buffer_t *buffer, hb_codepoint_t unichar, hb_codepoint_t glyph)
 {
+  /* This is very confusing indeed. */
   buffer->cur().glyph_index() = glyph;
-  buffer->output_glyph (unichar); /* This is very confusing indeed. */
+  (void) buffer->output_glyph (unichar);
   _hb_glyph_info_set_unicode_props (&buffer->prev(), buffer);
 }