diff --git a/qutebrowser/utils/ipc.py b/qutebrowser/utils/ipc.py
index 5c0b262c8..5c8e9abd9 100644
--- a/qutebrowser/utils/ipc.py
+++ b/qutebrowser/utils/ipc.py
@@ -51,6 +51,7 @@ def send_to_running_instance(cmdlist):
         log.init.info("Opening in existing instance")
         line = json.dumps(cmdlist) + '\n'
         socket.writeData(line.encode('utf-8'))
+        socket.waitForBytesWritten()
     else:
         return False