diff --git a/include/SDL_main.h b/include/SDL_main.h
index 2dd62b524..cf8b728dc 100644
--- a/include/SDL_main.h
+++ b/include/SDL_main.h
@@ -66,7 +66,7 @@ extern DECLSPEC void SDLCALL SDL_SetModuleHandle(void *hInst);
 /* This can also be called, but is no longer necessary */
 extern DECLSPEC int SDLCALL SDL_RegisterApp(char *name, Uint32 style, void *hInst);
 /* This can also be called, but is no longer necessary (SDL_Quit calls it) */
-extern DECLSPEC void SDLCALL SDL_UnregisterApp();
+extern DECLSPEC void SDLCALL SDL_UnregisterApp(void);
 #ifdef __cplusplus
 }
 #endif