diff --git a/gerrit-pgm/src/main/resources/com/google/gerrit/pgm/gerrit.sh b/gerrit-pgm/src/main/resources/com/google/gerrit/pgm/gerrit.sh
index 06d524a..e23984d 100755
--- a/gerrit-pgm/src/main/resources/com/google/gerrit/pgm/gerrit.sh
+++ b/gerrit-pgm/src/main/resources/com/google/gerrit/pgm/gerrit.sh
@@ -416,7 +416,7 @@
       fi
 
       sleep 2
-      let TIMEOUT=$TIMEOUT-2
+      TIMEOUT=$(($TIMEOUT - 2))
     done
 
     echo FAILED
@@ -447,7 +447,7 @@
       while running "$GERRIT_PID" && test $TIMEOUT -gt 0 ; do
         kill $PID 2>/dev/null
         sleep 1
-        let TIMEOUT=$TIMEOUT-1
+        TIMEOUT=$(($TIMEOUT - 1))
       done
       test $TIMEOUT -gt 0 || kill -9 $PID 2>/dev/null
       rm -f "$GERRIT_PID" "$GERRIT_RUN"