diff --git a/src/hb-coretext.cc b/src/hb-coretext.cc
index 4a1e14ceb..4a4517528 100644
--- a/src/hb-coretext.cc
+++ b/src/hb-coretext.cc
@@ -897,6 +897,8 @@ retry:
 		   * for this one. */
 		  continue;
 	      }
+	      if (buffer->unicode->is_default_ignorable (ch))
+	        continue;
 
 	      info->codepoint = notdef;
 	      info->cluster = log_clusters[j];
diff --git a/src/hb-ot-shape.cc b/src/hb-ot-shape.cc
index a0b503ab0..07adb04f6 100644
--- a/src/hb-ot-shape.cc
+++ b/src/hb-ot-shape.cc
@@ -676,7 +676,7 @@ hb_ot_hide_default_ignorables (hb_ot_shape_context_t *c)
 	pos[i].y_advance = 0;
       }
       else
-	continue; /* Delete it. */
+	continue; /* Delete it. XXX Merge clusters? */
     }
     if (j != i)
     {