diff --git a/src/hb-style.cc b/src/hb-style.cc
index dd54fdd9d..afa4a9f8f 100644
--- a/src/hb-style.cc
+++ b/src/hb-style.cc
@@ -63,6 +63,9 @@ hb_style_get_value (hb_font_t *font, hb_style_tag_t style_tag)
   }
 #endif
 
+  if (style_tag == HB_STYLE_TAG_OPTICAL_SIZE && font->ptem)
+    return font->ptem;
+
   /* STAT */
   float value;
   if (face->table.STAT->get_value (style_tag, &value))
diff --git a/test/api/test-style.c b/test/api/test-style.c
index 23d2e41da..9225a0a09 100644
--- a/test/api/test-style.c
+++ b/test/api/test-style.c
@@ -70,6 +70,9 @@ test_face_fdsc (void)
   assert_cmpfloat (hb_style_get_value (font, HB_STYLE_TAG_WIDTH), 100);
   assert_cmpfloat (hb_style_get_value (font, HB_STYLE_TAG_WEIGHT), 400);
 
+  hb_font_set_ptem (font, 36);
+  assert_cmpfloat (hb_style_get_value (font, HB_STYLE_TAG_OPTICAL_SIZE), 36);
+
   hb_font_destroy (font);
   hb_face_destroy (face);
 }