diff --git a/src/graph/session/GraphSessionManager.cpp b/src/graph/session/GraphSessionManager.cpp
index a5faa5c22b5..c11003d9eb1 100644
--- a/src/graph/session/GraphSessionManager.cpp
+++ b/src/graph/session/GraphSessionManager.cpp
@@ -151,7 +151,10 @@ void GraphSessionManager::threadFunc() {
 // TODO(dutor) Now we do a brute-force scanning, of course we could make it more
 // efficient.
 void GraphSessionManager::reclaimExpiredSessions() {
+  DCHECK_GT(FLAGS_session_idle_timeout_secs, 0);
   if (FLAGS_session_idle_timeout_secs == 0) {
+    LOG(ERROR) << "Program should not reach here, session_idle_timeout_secs should be an integer "
+                  "between 1 and 604800";
     return;
   }
 
diff --git a/tests/admin/test_configs.py b/tests/admin/test_configs.py
index 3baaedba9ec..600d4f0eee2 100644
--- a/tests/admin/test_configs.py
+++ b/tests/admin/test_configs.py
@@ -37,6 +37,8 @@ def test_configs(self):
         self.check_resp_succeeded(resp)
 
         # update flag to an invalid value, expected to fail
+        resp = self.client.execute('UPDATE CONFIGS graph:session_idle_timeout_secs={}'.format(0))
+        self.check_resp_failed(resp)
         resp = self.client.execute('UPDATE CONFIGS graph:session_idle_timeout_secs={}'.format(999999))
         self.check_resp_failed(resp)