diff --git a/tests/spark_config_test.py b/tests/spark_config_test.py
index 625706f..d87a930 100644
--- a/tests/spark_config_test.py
+++ b/tests/spark_config_test.py
@@ -1144,6 +1144,7 @@ def assert_app_name(
         def verify(output):
             key = 'spark.app.name'
             assert output[key] == expected_output
+            assert len(output[key]) <= 63
             return [key]
         return verify