diff --git a/test/run_all_tests.sh b/test/run_all_tests.sh
index 62687d77..af702441 100755
--- a/test/run_all_tests.sh
+++ b/test/run_all_tests.sh
@@ -45,5 +45,5 @@ for test in "${tests[@]}"; do
         exit ${ret}
     fi
     echo "PASS"
-    display=$(( ${display} + 1 ))
+    display=$(( display + 1 ))
 done