diff --git a/src/hb-ot-layout.cc b/src/hb-ot-layout.cc
index c80ca7d7f..3b7ea47ea 100644
--- a/src/hb-ot-layout.cc
+++ b/src/hb-ot-layout.cc
@@ -591,6 +591,31 @@ hb_ot_layout_collect_lookups (hb_face_t      *face,
   }
 }
 
+void
+hb_ot_layout_lookup_get_coverage (hb_face_t    *face,
+				  hb_tag_t      table_tag,
+				  unsigned int  lookup_index,
+				  hb_set_t     *glyphs /* OUT */)
+{
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return;
+
+  switch (table_tag)
+  {
+    case HB_OT_TAG_GSUB:
+    {
+      const OT::SubstLookup& l = hb_ot_layout_from_face (face)->gsub->get_lookup (lookup_index);
+      l.add_coverage (glyphs);
+      return;
+    }
+    case HB_OT_TAG_GPOS:
+    {
+      const OT::PosLookup& l = hb_ot_layout_from_face (face)->gpos->get_lookup (lookup_index);
+      l.add_coverage (glyphs);
+      return;
+    }
+  }
+}
+
 void
 hb_ot_layout_lookup_collect_glyphs (hb_face_t    *face,
 				    hb_tag_t      table_tag,
diff --git a/src/hb-ot-layout.h b/src/hb-ot-layout.h
index 134f1a6c1..07ccc051b 100644
--- a/src/hb-ot-layout.h
+++ b/src/hb-ot-layout.h
@@ -192,6 +192,12 @@ hb_ot_shape_plan_collect_lookups (hb_shape_plan_t *shape_plan,
 				  hb_tag_t         table_tag,
 				  hb_set_t        *lookup_indexes /* OUT */);
 
+void
+hb_ot_layout_lookup_get_coverage (hb_face_t    *face,
+				  hb_tag_t      table_tag,
+				  unsigned int  lookup_index,
+				  hb_set_t     *glyphs /* OUT */);
+
 void
 hb_ot_layout_lookup_collect_glyphs (hb_face_t    *face,
 				    hb_tag_t      table_tag,