diff --git a/key/goKey.h b/key/goKey.h
index 77c1927..c66338d 100644
--- a/key/goKey.h
+++ b/key/goKey.h
@@ -143,6 +143,8 @@ int CheckKeyCodes(char* k, MMKeyCode *key){
 
 	if (strlen(k) == 1) {
 		*key = keyCodeForChar(*k);
+		if (*key == K_NOT_A_KEY)
+			return -2;
 		return 0;
 	}
 
diff --git a/key/keycode_c.h b/key/keycode_c.h
index cb19f51..25891a6 100644
--- a/key/keycode_c.h
+++ b/key/keycode_c.h
@@ -79,7 +79,7 @@ MMKeyCode keyCodeForChar(const char c){
 													128,
 													&kCFCopyStringDictionaryKeyCallBacks,
 													NULL);
-			if (charToCodeDict == NULL) return UINT16_MAX;
+			if (charToCodeDict == NULL) return K_NOT_A_KEY;
 
 			/* Loop through every keycode (0 - 127) to find its current mapping. */
 			for (i = 0; i < 128; ++i) {
@@ -100,9 +100,18 @@ MMKeyCode keyCodeForChar(const char c){
 		}
 
 		CFRelease(charStr);
+
+		if (code == UINT16_MAX) {
+			return K_NOT_A_KEY;
+		}
+
 		return (MMKeyCode)code;
 	#elif defined(IS_WINDOWS)
-		return VkKeyScan(c);
+		CGKeyCode code;
+		code = VkKeyScan(c);
+		if (code == 0xFFFF)
+			return K_NOT_A_KEY;
+		return code;
 	#elif defined(USE_X11)
 		MMKeyCode code;
 
@@ -125,6 +134,9 @@ MMKeyCode keyCodeForChar(const char c){
 			}
 		}
 
+		if (code == NoSymbol)
+			return K_NOT_A_KEY;
+
 		return code;
 	#endif
 }