diff --git a/src/System.h b/src/System.h
index 1e971e12..49e8ab83 100644
--- a/src/System.h
+++ b/src/System.h
@@ -111,8 +111,8 @@ extern void Sm60FPS_Sleep();
 extern void DbgMsg(const char *msg, ...);
 extern void winlog(const char *,...);
 
-extern void dbgOutput(const char *s, u32 addr);
-extern void dbgSignal(int sig,int number);
+extern void (*dbgOutput)(const char *s, u32 addr);
+extern void (*dbgSignal)(int sig,int number);
 
 extern bool systemSoundOn;
 extern u16 systemColorMap16[0x10000];