diff --git a/src/hb-font.h b/src/hb-font.h
index 7b3f1edb5..f33e56feb 100644
--- a/src/hb-font.h
+++ b/src/hb-font.h
@@ -126,7 +126,7 @@ typedef void (*hb_font_get_glyph_advance_func_t) (hb_font_t *font, hb_face_t *fa
 						  hb_position_t *x_advance, hb_position_t *y_advance);
 typedef void (*hb_font_get_glyph_extents_func_t) (hb_font_t *font, hb_face_t *face, const void *user_data,
 						  hb_codepoint_t glyph,
-						  hb_glyph_extents_t *metrics);
+						  hb_glyph_extents_t *extents);
 typedef hb_bool_t (*hb_font_get_contour_point_func_t) (hb_font_t *font, hb_face_t *face, const void *user_data,
 						       unsigned int point_index, hb_codepoint_t glyph,
 						       hb_position_t *x, hb_position_t *y);
@@ -185,7 +185,7 @@ hb_font_get_glyph_advance (hb_font_t *font, hb_face_t *face,
 void
 hb_font_get_glyph_extents (hb_font_t *font, hb_face_t *face,
 			   hb_codepoint_t glyph,
-			   hb_glyph_extents_t *metrics);
+			   hb_glyph_extents_t *extents);
 
 hb_bool_t
 hb_font_get_contour_point (hb_font_t *font, hb_face_t *face,