Upstream commit #24477.
diff -up krb5-1.9/src/slave/kpropd.c krb5-1.9/src/slave/kpropd.c
--- krb5-1.9/src/slave/kpropd.c	2011-03-18 13:14:24.020999947 -0400
+++ krb5-1.9/src/slave/kpropd.c	2011-03-18 13:14:34.159999947 -0400
@@ -993,7 +993,7 @@ unsigned int backoff_from_master(int *cn
     btime = (unsigned int)(2<<(*cnt));
     if (btime > MAX_BACKOFF) {
         btime = MAX_BACKOFF;
-        *cnt--;
+        (*cnt)--;
     }
 
     return (btime);