diff --git a/src/hb-ot-layout-common-private.hh b/src/hb-ot-layout-common-private.hh
index bfb3bdbfd..0696e470b 100644
--- a/src/hb-ot-layout-common-private.hh
+++ b/src/hb-ot-layout-common-private.hh
@@ -686,6 +686,14 @@ struct ClassDefFormat1
     return TRACE_RETURN (c->check_struct (this) && classValue.sanitize (c));
   }
 
+  template <typename set_t>
+  inline void add_class (set_t *glyphs, unsigned int klass) const {
+    unsigned int count = classValue.len;
+    for (unsigned int i = 0; i < count; i++)
+      if (classValue[i] == klass)
+        glyphs->add (startGlyph + i);
+  }
+
   inline bool intersects_class (const hb_set_t *glyphs, unsigned int klass) const {
     unsigned int count = classValue.len;
     for (unsigned int i = 0; i < count; i++)
@@ -721,6 +729,14 @@ struct ClassDefFormat2
     return TRACE_RETURN (rangeRecord.sanitize (c));
   }
 
+  template <typename set_t>
+  inline void add_class (set_t *glyphs, unsigned int klass) const {
+    unsigned int count = rangeRecord.len;
+    for (unsigned int i = 0; i < count; i++)
+      if (rangeRecord[i].value == klass)
+        rangeRecord[i].add_coverage (glyphs);
+  }
+
   inline bool intersects_class (const hb_set_t *glyphs, unsigned int klass) const {
     unsigned int count = rangeRecord.len;
     for (unsigned int i = 0; i < count; i++)
@@ -761,6 +777,14 @@ struct ClassDef
     }
   }
 
+  inline void add_class (hb_set_t *glyphs, unsigned int klass) const {
+    switch (u.format) {
+    case 1: u.format1.add_class (glyphs, klass); return;
+    case 2: u.format2.add_class (glyphs, klass); return;
+    default:return;
+    }
+  }
+
   inline bool intersects_class (const hb_set_t *glyphs, unsigned int klass) const {
     switch (u.format) {
     case 1: return u.format1.intersects_class (glyphs, klass);
diff --git a/src/hb-ot-layout-gdef-table.hh b/src/hb-ot-layout-gdef-table.hh
index e7fb42fa9..0ab2bc28d 100644
--- a/src/hb-ot-layout-gdef-table.hh
+++ b/src/hb-ot-layout-gdef-table.hh
@@ -337,6 +337,8 @@ struct GDEF
   inline bool has_glyph_classes (void) const { return glyphClassDef != 0; }
   inline unsigned int get_glyph_class (hb_codepoint_t glyph) const
   { return (this+glyphClassDef).get_class (glyph); }
+  inline void get_glyphs_in_class (unsigned int klass, hb_set_t *glyphs) const
+  { (this+glyphClassDef).add_class (glyphs, klass); }
 
   inline bool has_mark_attachment_types (void) const { return markAttachClassDef != 0; }
   inline unsigned int get_mark_attachment_type (hb_codepoint_t glyph) const
diff --git a/src/hb-ot-layout.cc b/src/hb-ot-layout.cc
index 8b827a6ba..a0c9fe822 100644
--- a/src/hb-ot-layout.cc
+++ b/src/hb-ot-layout.cc
@@ -128,6 +128,14 @@ hb_ot_layout_get_glyph_class (hb_face_t      *face,
   return (hb_ot_layout_glyph_class_t) _get_gdef (face).get_glyph_class (glyph);
 }
 
+void
+hb_ot_layout_get_glyphs_in_class (hb_face_t                  *face,
+				  hb_ot_layout_glyph_class_t  klass,
+				  hb_set_t                   *glyphs /* OUT */)
+{
+  return _get_gdef (face).get_glyphs_in_class (klass, glyphs);
+}
+
 unsigned int
 hb_ot_layout_get_attach_points (hb_face_t      *face,
 				hb_codepoint_t  glyph,
diff --git a/src/hb-ot-layout.h b/src/hb-ot-layout.h
index 0128534ca..4a023c4eb 100644
--- a/src/hb-ot-layout.h
+++ b/src/hb-ot-layout.h
@@ -62,11 +62,10 @@ hb_ot_layout_glyph_class_t
 hb_ot_layout_get_glyph_class (hb_face_t      *face,
 			      hb_codepoint_t  glyph);
 
-#ifdef HB_NOT_IMPLEMENTED
-Xhb_ot_layout_get_glyphs_in_class (hb_face_t                  *face,
+void
+hb_ot_layout_get_glyphs_in_class (hb_face_t                  *face,
 				  hb_ot_layout_glyph_class_t  klass,
 				  hb_set_t                   *glyphs /* OUT */);
-#endif
 
 
 /* Not that useful.  Provides list of attach points for a glyph that a