cast away warnings
diff --git a/Modules/operator.c b/Modules/operator.c
index ac3caf8..7cbb45e 100644
--- a/Modules/operator.c
+++ b/Modules/operator.c
@@ -309,8 +309,8 @@
 
     /* Unicode string */
     if (PyUnicode_Check(a) && PyUnicode_Check(b)) {
-        rc = _tscmp(PyUnicode_AS_DATA(a),
-                    PyUnicode_AS_DATA(b),
+        rc = _tscmp((const unsigned char *)PyUnicode_AS_DATA(a),
+                    (const unsigned char *)PyUnicode_AS_DATA(b),
                     PyUnicode_GET_DATA_SIZE(a),
                     PyUnicode_GET_DATA_SIZE(b));
     }