diff --git a/Source/Project64/N64 System/Cheat Class.cpp b/Source/Project64/N64 System/Cheat Class.cpp
index 8432f5573..efa97355a 100644
--- a/Source/Project64/N64 System/Cheat Class.cpp	
+++ b/Source/Project64/N64 System/Cheat Class.cpp	
@@ -15,6 +15,8 @@
 enum { WM_EDITCHEAT           = WM_USER + 0x120 };
 enum { UM_CHANGECODEEXTENSION = WM_USER + 0x121 };
 
+extern int is_valid_hex_digit(char symbol);
+
 CCheats::CCheats (const CN64Rom * Rom ) :
 	m_Rom(Rom),
 	m_rcList(new RECT),
@@ -1845,7 +1847,7 @@ stdstr CCheats::ReadOptionsString(HWND hDlg, bool &/*validcodes*/, bool &validop
 			case 1: //option = lower byte
 				if (len >= 2) {
 					for (i=0; i<2; i++) {
-						if (!(((str[i] >= 'a') && (str[i] <= 'f')) || ((str[i] >= 'A') && (str[i] <= 'F')) || ((str[i] >= '0') && (str[i] <= '9')))) {
+						if (!is_valid_hex_digit(str[i])) {
 							validoptions = false;
 							break;
 						}
@@ -1878,7 +1880,7 @@ stdstr CCheats::ReadOptionsString(HWND hDlg, bool &/*validcodes*/, bool &validop
 			case 2: //option = word
 				if (len >= 4) {
 					for (i=0; i<4; i++) {
-						if (!(((str[i] >= 'a') && (str[i] <= 'f')) || ((str[i] >= 'A') && (str[i] <= 'F')) || ((str[i] >= '0') && (str[i] <= '9')))) {
+						if (!is_valid_hex_digit(str[i])) {
 							validoptions = false;
 							break;
 						}
@@ -1913,5 +1915,13 @@ stdstr CCheats::ReadOptionsString(HWND hDlg, bool &/*validcodes*/, bool &validop
 	return optionsstring;
 }
 
-
-
+int is_valid_hex_digit(char symbol)
+{
+    if (
+        ((symbol >= 'a') && (symbol <= 'f'))
+     || ((symbol >= 'A') && (symbol <= 'F'))
+     || ((symbol >= '0') && (symbol <= '9'))
+    )
+        return 1;
+    return 0;
+}