diff --git a/UnixBench/src/arith.c b/UnixBench/src/arith.c
index bbacb08..05fab70 100644
--- a/UnixBench/src/arith.c
+++ b/UnixBench/src/arith.c
@@ -35,7 +35,7 @@ char SCCSid[] = "@(#) @(#)arith.c:3.3 -- 5/15/91 19:30:19";
 
 int dumb_stuff(int);
 
-unsigned long iter;
+volatile unsigned long iter;
 
 /* this function is called when the alarm expires */
 void report()