diff --git a/tests-e2e/run-tests.sh b/tests-e2e/run-tests.sh
index b53ba13..6bd39dc 100755
--- a/tests-e2e/run-tests.sh
+++ b/tests-e2e/run-tests.sh
@@ -21,7 +21,7 @@ do
   fi
   echo "Waiting (total ${attempts}s) for server to start..."
   sleep 1
-  ((attempts++))
+  attempts=$((attempts+1))
 done
 
 go test "$@"
\ No newline at end of file