diff --git a/tools/test-networkmanager-service.py b/tools/test-networkmanager-service.py
index 2121bb2b27..fd3c44a0ff 100755
--- a/tools/test-networkmanager-service.py
+++ b/tools/test-networkmanager-service.py
@@ -1392,13 +1392,12 @@ def main():
         raise AssertionError("Failure to request D-Bus name org.freedesktop.NetworkManager")
 
     # Watch stdin; if it closes, assume our parent has crashed, and exit
-    io = GLib.IOChannel(0)
-    id1 = io.add_watch(GLib.IOCondition.HUP,
-                       lambda io, condition: gl.mainloop.quit())
+    id1 = GLib.IOChannel(0).add_watch(GLib.IOCondition.HUP,
+                                      lambda io, condition: gl.mainloop.quit() or True)
 
     # also quit after inactivity to ensure we don't stick around if the above fails somehow
     id2 = GLib.timeout_add_seconds(20,
-                                   lambda: gl.mainloop.quit())
+                                   lambda: gl.mainloop.quit() or True)
 
     gl.mainloop.run()