diff --git a/src/xrc/xmlres.cpp b/src/xrc/xmlres.cpp
index 5b41a453aa..88fa86ab4a 100644
--- a/src/xrc/xmlres.cpp
+++ b/src/xrc/xmlres.cpp
@@ -1996,9 +1996,9 @@ static XRCID_record *XRCID_Records[XRCID_TABLE_SIZE] = {NULL};
 
 static int XRCID_Lookup(const char *str_id, int value_if_not_found = wxID_NONE)
 {
-    int index = 0;
+    unsigned int index = 0;
 
-    for (const char *c = str_id; *c != '\0'; c++) index += (int)*c;
+    for (const char *c = str_id; *c != '\0'; c++) index += (unsigned int)*c;
     index %= XRCID_TABLE_SIZE;
 
     XRCID_record *oldrec = NULL;