diff --git a/webserver.py b/webserver.py
index d743f22..529be81 100755
--- a/webserver.py
+++ b/webserver.py
@@ -91,9 +91,9 @@ class Server:
             tags['device'] = devices[0] if len(devices) == 1 else devices
         return streams, tags, ','.join(device_names)
 
-    def register_client(self, instrument=None, stream=None, device=None, history_only='0'):
+    def register_client(self, instrument=None, stream=None, device=None, history_only=None):
         streams, tags, device_name = self.lookup_streams(instrument, stream, device)
-        if history_only != '0':
+        if (history_only or '0') != '0':
             # create dummy client
             client = self.client_cls(self, [], '', '')
         else: