diff --git a/src/hb-buffer-private.hh b/src/hb-buffer-private.hh
index 4fae88454..73535d4b4 100644
--- a/src/hb-buffer-private.hh
+++ b/src/hb-buffer-private.hh
@@ -65,6 +65,13 @@ HB_INTERNAL void
 _hb_buffer_replace_glyph (hb_buffer_t *buffer,
 			  hb_codepoint_t glyph_index);
 
+HB_INTERNAL void
+_hb_buffer_output_glyph (hb_buffer_t *buffer,
+			 hb_codepoint_t glyph_index);
+
+HB_INTERNAL void
+_hb_buffer_skip_glyph (hb_buffer_t *buffer);
+
 HB_INTERNAL void
 _hb_buffer_next_glyph (hb_buffer_t *buffer);
 
@@ -125,6 +132,9 @@ struct _hb_buffer_t {
   { _hb_buffer_replace_glyphs_be16 (this, num_in, num_out, glyph_data_be); }
   inline void replace_glyph (hb_codepoint_t glyph_index)
   { _hb_buffer_replace_glyph (this, glyph_index); }
+  inline void output_glyph (hb_codepoint_t glyph_index)
+  { _hb_buffer_output_glyph (this, glyph_index); }
+  inline void skip_glyph (void) { _hb_buffer_skip_glyph (this); }
 
   inline void reset_masks (hb_mask_t mask)
   {
diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index b65ddbb4c..174d8e8d4 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -404,8 +404,8 @@ _hb_buffer_replace_glyphs_be16 (hb_buffer_t *buffer,
 }
 
 void
-_hb_buffer_replace_glyph (hb_buffer_t *buffer,
-			  hb_codepoint_t glyph_index)
+_hb_buffer_output_glyph (hb_buffer_t *buffer,
+			 hb_codepoint_t glyph_index)
 {
   hb_glyph_info_t *info;
 
@@ -420,10 +420,23 @@ _hb_buffer_replace_glyph (hb_buffer_t *buffer,
   info = &buffer->out_info[buffer->out_len];
   info->codepoint = glyph_index;
 
-  buffer->i++;
   buffer->out_len++;
 }
 
+void
+_hb_buffer_replace_glyph (hb_buffer_t *buffer,
+			  hb_codepoint_t glyph_index)
+{
+  _hb_buffer_output_glyph (buffer, glyph_index);
+  _hb_buffer_skip_glyph (buffer);
+}
+
+void
+_hb_buffer_skip_glyph (hb_buffer_t *buffer)
+{
+  buffer->i++;
+}
+
 void
 _hb_buffer_next_glyph (hb_buffer_t *buffer)
 {
diff --git a/src/hb-ot-shape.cc b/src/hb-ot-shape.cc
index 306beb3b4..33123d40b 100644
--- a/src/hb-ot-shape.cc
+++ b/src/hb-ot-shape.cc
@@ -264,7 +264,7 @@ hb_map_glyphs (hb_font_t    *font,
     if (unlikely (is_variation_selector (buffer->info[buffer->i + 1].codepoint))) {
       hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, buffer->info[buffer->i + 1].codepoint, &glyph);
       buffer->replace_glyph (glyph);
-      buffer->i++;
+      buffer->skip_glyph ();
     } else {
       hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, 0, &glyph);
       buffer->replace_glyph (glyph);