Eliminate compiler warning.
diff --git a/cups/ipp-support.c b/cups/ipp-support.c
index b6431e1..b49ac0d 100644
--- a/cups/ipp-support.c
+++ b/cups/ipp-support.c
@@ -2125,7 +2125,7 @@
   * See if the operation ID is a known value...
   */
 
-  if (op >= IPP_OP_PRINT_JOB && op < (sizeof(ipp_std_ops) / sizeof(ipp_std_ops[0])))
+  if (op >= IPP_OP_PRINT_JOB && op < (ipp_op_t)(sizeof(ipp_std_ops) / sizeof(ipp_std_ops[0])))
     return (ipp_std_ops[op]);
   else if (op == IPP_OP_PRIVATE)
     return ("windows-ext");