diff --git a/src/debug/debug.cpp b/src/debug/debug.cpp
index a73d86c4..992ed4a4 100644
--- a/src/debug/debug.cpp
+++ b/src/debug/debug.cpp
@@ -1725,7 +1725,10 @@ Bit32u DEBUG_CheckKeys(void) {
 		}
 		if (ret<0) return ret;
 		if (ret>0) {
-			ret=(*CallBack_Handlers[ret])();
+			if (GCC_UNLIKELY(ret >= CB_MAX)) 
+				ret = 0;
+			else
+				ret = (*CallBack_Handlers[ret])();
 			if (ret) {
 				exitLoop=true;
 				CPU_Cycles=CPU_CycleLeft=0;
diff --git a/src/dosbox.cpp b/src/dosbox.cpp
index 34e848fd..d95de3f8 100644
--- a/src/dosbox.cpp
+++ b/src/dosbox.cpp
@@ -128,10 +128,11 @@ static Bitu Normal_Loop(void) {
 	Bits ret;
 	while (1) {
 		if (PIC_RunQueue()) {
-			ret=(*cpudecoder)();
+			ret = (*cpudecoder)();
 			if (GCC_UNLIKELY(ret<0)) return 1;
 			if (ret>0) {
-				Bitu blah=(*CallBack_Handlers[ret])();
+				if (GCC_UNLIKELY(ret >= CB_MAX)) return 0;
+				Bitu blah = (*CallBack_Handlers[ret])();
 				if (GCC_UNLIKELY(blah)) return blah;
 			}
 #if C_DEBUG