diff --git a/tests/venv/start/start-script/verify b/tests/venv/start/start-script/verify
index 8422ceba..b466ab08 100644
--- a/tests/venv/start/start-script/verify
+++ b/tests/venv/start/start-script/verify
@@ -1,7 +1,8 @@
 #!/bin/bash
 set -euo pipefail
 
-if [ "$TEST_START_VAR" != "var is set" ]
+# set value of TEST_START_VAR to empty string when it is not defined
+if [ "${TEST_START_VAR:-}" != "var is set" ]
 then
   echo "TEST_START_VAR is not set"
   exit 1