diff --git a/src/hb-font.h b/src/hb-font.h
index 15dd351b04ae688b73f37a8401d9837a3aa71bc8..e020bd838a95efe5521111b36d1c76b1530cdaaa 100644
--- a/src/hb-font.h
+++ b/src/hb-font.h
@@ -98,6 +98,15 @@ hb_font_funcs_make_immutable (hb_font_funcs_t *ffuncs);
 /* funcs */
 
 typedef struct _hb_glyph_metrics_t hb_glyph_metrics_t;
+struct _hb_glyph_metrics_t
+{
+    hb_position_t x_advance;
+    hb_position_t y_advance;
+    hb_position_t x_offset;
+    hb_position_t y_offset;
+    hb_position_t width;
+    hb_position_t height;
+};
 
 typedef hb_codepoint_t (*hb_font_get_glyph_func_t) (hb_font_t *font, hb_face_t *face, const void *user_data,
 						    hb_codepoint_t unicode, hb_codepoint_t variant_selector);