diff --git a/src/sdf/ftsdf.h b/src/sdf/ftsdf.h
index ce5f8ec68..c10c4b2c7 100644
--- a/src/sdf/ftsdf.h
+++ b/src/sdf/ftsdf.h
@@ -67,6 +67,9 @@ FT_BEGIN_HEADER
   /* rasterizer to convert outline to SDF */
   FT_EXPORT_VAR( const FT_Raster_Funcs ) ft_sdf_raster;
 
+  /* rasterizer to convert bitmap to SDF */
+  FT_EXPORT_VAR( const FT_Raster_Funcs ) ft_bitmap_sdf_raster;
+
 FT_END_HEADER
 
 #endif /* FTSDF_H_ */