diff --git a/src/core/os2/geniconv/os2iconv.c b/src/core/os2/geniconv/os2iconv.c
index 2aed47f05..c24cc54dc 100644
--- a/src/core/os2/geniconv/os2iconv.c
+++ b/src/core/os2/geniconv/os2iconv.c
@@ -73,7 +73,8 @@ static int _createUconvObj(const char *code, UconvObject *uobj)
 {
     UniChar uc_code[MAX_CP_NAME_LEN];
     int i;
-    const char *ch = code;
+    const unsigned char *ch =
+         (const unsigned char *)code;
 
     if (code == NULL)
         uc_code[0] = 0;