diff --git a/notebook/notebookapp.py b/notebook/notebookapp.py
index c180bea4d2..05e44cf29f 100755
--- a/notebook/notebookapp.py
+++ b/notebook/notebookapp.py
@@ -1839,7 +1839,7 @@ def list_running_servers(runtime_dir=None):
         return
 
     for file_name in os.listdir(runtime_dir):
-        if file_name.startswith('nbserver-'):
+        if re.match('nbserver-(.+).json', file_name):
             with io.open(os.path.join(runtime_dir, file_name), encoding='utf-8') as f:
                 info = json.load(f)
 
diff --git a/notebook/tests/test_notebookapp.py b/notebook/tests/test_notebookapp.py
index 0c277e80d9..ff34a97776 100644
--- a/notebook/tests/test_notebookapp.py
+++ b/notebook/tests/test_notebookapp.py
@@ -25,6 +25,8 @@
 from notebook.auth.security import passwd_check
 NotebookApp = notebookapp.NotebookApp
 
+from .launchnotebook import NotebookTestBase
+
 
 def test_help_output():
     """ipython notebook --help-all works"""
@@ -183,3 +185,10 @@ def list_running_servers(runtime_dir):
             app.start()
         nt.assert_equal(exc.exception.code, 1)
     nt.assert_equal(len(app.servers_shut_down), 0)
+
+
+class NotebookAppTests(NotebookTestBase):
+    def test_list_running_servers(self):
+        servers = list(notebookapp.list_running_servers())
+        assert len(servers) >= 1
+        assert self.port in {info['port'] for info in servers}