diff --git a/src/ags.h b/src/ags.h
index 707f37f..5709a53 100644
--- a/src/ags.h
+++ b/src/ags.h
@@ -61,7 +61,7 @@ typedef enum {
 	TO_24B
 } ALPHA_DIB_COPY_TYPE;
 
-struct __surface {
+struct agsurface {
 	int no;      /* surface number, primary DIB is 0 */
 	
 	int width;   /* width of surface  */
@@ -78,7 +78,7 @@ struct __surface {
 	boolean has_pixel;
 
 };
-typedef struct __surface agsurface_t;
+typedef struct agsurface agsurface_t;
 
 #define GETOFFSET_PIXEL(suf, x, y) ((suf)->pixel + (y) * (suf)->bytes_per_line + (x) * (suf)->bytes_per_pixel)
 #define GETOFFSET_ALPHA(suf, x, y) ((suf)->alpha + (y) * (suf)->width + (x))
diff --git a/src/font.h b/src/font.h
index d91c364..4eb2e7c 100644
--- a/src/font.h
+++ b/src/font.h
@@ -34,6 +34,8 @@
 #define FONT_GOTHIC (0)
 #define FONT_MINCHO (1)
 
+struct agsurface;
+
 struct _FONT {
 	
 	boolean antialiase_on;
@@ -44,7 +46,7 @@ struct _FONT {
 	
 	void (*sel_font)(int type, int size);
 	
-	void *(*get_glyph)(unsigned char *str);
+	struct agsurface *(*get_glyph)(unsigned char *str);
 	
 	int (*draw_glyph)(int x, int y, unsigned char *str, int col);
 	
diff --git a/src/font_freetype2.c b/src/font_freetype2.c
index 8c385de..9bb489e 100644
--- a/src/font_freetype2.c
+++ b/src/font_freetype2.c
@@ -231,7 +231,7 @@ static void clear_canvas(void) {
 	memset(img_glyph.pixel, 0, GLYPH_PIXMAP_WIDTH * GLYPH_PIXMAP_HEIGHT);
 }
 
-static void *font_ttf_get_glyph(unsigned char *_msg) {
+static agsurface_t *font_ttf_get_glyph(unsigned char *_msg) {
 	FT_GlyphSlot   slot;
 	FT_UShort      code;
 	FT_Error       err;
diff --git a/src/font_sdlttf.c b/src/font_sdlttf.c
index 18b92fa..0d3f6fd 100644
--- a/src/font_sdlttf.c
+++ b/src/font_sdlttf.c
@@ -69,7 +69,7 @@ static void font_sdlttf_sel_font(int type, int size) {
 	}
 }
 
-static void *font_sdlttf_get_glyph(unsigned char *msg) {
+static agsurface_t *font_sdlttf_get_glyph(unsigned char *msg) {
 	static SDL_Surface *fs;
 	static agsurface_t result;
 
diff --git a/src/font_x11.c b/src/font_x11.c
index 86f312d..d47113f 100644
--- a/src/font_x11.c
+++ b/src/font_x11.c
@@ -151,7 +151,7 @@ static agsurface_t *get_drawn_glyph(const char *str, int w) {
 	return dst;
 }
 
-static void *font_x11_get_glyph(unsigned char *str) {
+static agsurface_t *font_x11_get_glyph(unsigned char *str) {
 	agsurface_t *dst;
 	int w;
 	BYTE *conv;