diff --git a/src/gen-vowel-constraints.py b/src/gen-vowel-constraints.py
index 44f4a27ab..2abbbaeca 100755
--- a/src/gen-vowel-constraints.py
+++ b/src/gen-vowel-constraints.py
@@ -223,11 +223,7 @@ print ('    default:')
 print ('      break;')
 print ('  }')
 print ('  if (processed)')
-print ('  {')
-print ('    if (buffer->idx < count)')
-print ('      buffer->next_glyph ();')
 print ('    buffer->swap_buffers ();')
-print ('  }')
 print ('}')
 
 print ()
diff --git a/src/hb-aat-layout-common.hh b/src/hb-aat-layout-common.hh
index fb2cc8359..3e83673c8 100644
--- a/src/hb-aat-layout-common.hh
+++ b/src/hb-aat-layout-common.hh
@@ -835,11 +835,7 @@ struct StateTableDriver
     }
 
     if (!c->in_place)
-    {
-      for (; buffer->successful && buffer->idx < buffer->len;)
-	buffer->next_glyph ();
       buffer->swap_buffers ();
-    }
   }
 
   public:
diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index 4dcc95660..2e0e3f5f6 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -333,6 +333,9 @@ hb_buffer_t::swap_buffers ()
 {
   if (unlikely (!successful)) return;
 
+  assert (idx <= len);
+  next_glyphs (len - idx);
+
   assert (have_output);
   have_output = false;
 
diff --git a/src/hb-ot-shape-complex-vowel-constraints.cc b/src/hb-ot-shape-complex-vowel-constraints.cc
index 1af546e4f..9f8f17f1a 100644
--- a/src/hb-ot-shape-complex-vowel-constraints.cc
+++ b/src/hb-ot-shape-complex-vowel-constraints.cc
@@ -452,11 +452,7 @@ _hb_preprocess_text_vowel_constraints (const hb_ot_shape_plan_t *plan HB_UNUSED,
       break;
   }
   if (processed)
-  {
-    if (buffer->idx < count)
-      buffer->next_glyph ();
     buffer->swap_buffers ();
-  }
 }
 
 
diff --git a/src/hb-ot-shape.cc b/src/hb-ot-shape.cc
index 7d9055845..92831e022 100644
--- a/src/hb-ot-shape.cc
+++ b/src/hb-ot-shape.cc
@@ -535,8 +535,6 @@ hb_insert_dotted_circle (hb_buffer_t *buffer, hb_font_t *font)
   info.cluster = buffer->cur().cluster;
   info.mask = buffer->cur().mask;
   buffer->output_info (info);
-  while (buffer->idx < buffer->len && buffer->successful)
-    buffer->next_glyph ();
   buffer->swap_buffers ();
 }