2 files changed, 3 insertions, 3 deletions
diff --git a/sdl.cpp b/sdl.cpp
index 33fc6e6af5..316fb2af59 100644
--- a/sdl.cpp
+++ b/sdl.cpp
@@ -97,7 +97,7 @@ public:
 	uint32 property(int param, Property *value);
 
 	// Add a callback timer
-	void set_timer(int timer, void* callback);
+	void set_timer(int timer, int (*callback)(int));
 
 	static OSystem *create(int gfx_mode, bool full_screen);
 
@@ -229,7 +229,7 @@ OSystem *OSystem_SDL::create(int gfx_mode, bool full_screen) {
 	return syst;
 }
 
-void OSystem_SDL::set_timer(int timer, void* callback) {
+void OSystem_SDL::set_timer(int timer, int (*callback)(int)) {
 	SDL_SetTimer(timer, (SDL_TimerCallback) callback);
 }
 OSystem *OSystem_SDL_create(int gfx_mode, bool full_screen) {
diff --git a/system.h b/system.h
index 59088d62e6..5a8855d1fa 100644
--- a/system.h
+++ b/system.h
@@ -137,7 +137,7 @@ public:
 	virtual void update_cdrom() = 0;
 
 	// Add a new callback timer
-	virtual void set_timer(int timer, void* callback) = 0;
+	virtual void set_timer(int timer, int (*callback)(int)) = 0;
 
 	// Quit
 	virtual void quit() = 0;