diff --git a/src/hb-subset-glyf.cc b/src/hb-subset-glyf.cc
index e0ae5d808..6581754b5 100644
--- a/src/hb-subset-glyf.cc
+++ b/src/hb-subset-glyf.cc
@@ -74,46 +74,30 @@ write_glyf_prime (const OT::glyf::accelerator_t &glyf,
   return true;
 }
 
-/**
- * hb_subset_glyf:
- * Subsets the glyph table according to a provided plan.
- *
- * Return value: subsetted glyf table.
- *
- * Since: 1.7.5
- **/
 bool
-hb_subset_glyf (hb_subset_plan_t *plan,
-                hb_face_t        *face,
-                hb_blob_t       **glyf_prime /* OUT */)
+_hb_subset_glyf (const OT::glyf::accelerator_t  &glyf,
+                 const char                     *glyf_data,
+                 hb_set_t                       *glyphs_to_retain,
+                 hb_blob_t                     **glyf_prime /* OUT */)
 {
   // TODO(grieger): Sanity check writes to make sure they are in-bounds.
   // TODO(grieger): Sanity check allocation size for the new table.
   // TODO(grieger): Subset loca simultaneously.
 
-  hb_blob_t *glyf_blob = OT::Sanitizer<OT::glyf>().sanitize (face->reference_table (HB_OT_TAG_glyf));
-  const char *glyf_data = hb_blob_get_data(glyf_blob, nullptr);
-
-  OT::glyf::accelerator_t glyf;
-  glyf.init(face);
-
   unsigned int glyf_prime_size;
   if (!calculate_glyf_prime_size (glyf,
-                                  plan->glyphs_to_retain,
+                                  glyphs_to_retain,
                                   &glyf_prime_size)) {
-    glyf.fini();
     return false;
   }
 
   char *glyf_prime_data = (char *) calloc (glyf_prime_size, 1);
-  if (!write_glyf_prime (glyf, glyf_data, plan->glyphs_to_retain, glyf_prime_size,
+  if (!write_glyf_prime (glyf, glyf_data, glyphs_to_retain, glyf_prime_size,
                          glyf_prime_data)) {
-    glyf.fini();
     free (glyf_prime_data);
     return false;
   }
 
-  glyf.fini();
   *glyf_prime = hb_blob_create (glyf_prime_data,
                                 glyf_prime_size,
                                 HB_MEMORY_MODE_READONLY,
@@ -121,3 +105,27 @@ hb_subset_glyf (hb_subset_plan_t *plan,
                                 free);
   return true;
 }
+
+/**
+ * hb_subset_glyf:
+ * Subsets the glyph table according to a provided plan.
+ *
+ * Return value: subsetted glyf table.
+ *
+ * Since: 1.7.5
+ **/
+bool
+hb_subset_glyf (hb_subset_plan_t *plan,
+                hb_face_t        *face,
+                hb_blob_t       **glyf_prime /* OUT */)
+{
+  hb_blob_t *glyf_blob = OT::Sanitizer<OT::glyf>().sanitize (face->reference_table (HB_OT_TAG_glyf));
+  const char *glyf_data = hb_blob_get_data(glyf_blob, nullptr);
+
+  OT::glyf::accelerator_t glyf;
+  glyf.init(face);
+  bool result = _hb_subset_glyf (glyf, glyf_data, plan->glyphs_to_retain, glyf_prime);
+  glyf.fini();
+
+  return result;
+}