diff --git a/mitmproxy/script/concurrent.py b/mitmproxy/script/concurrent.py
index 366929a5d..87cdca968 100644
--- a/mitmproxy/script/concurrent.py
+++ b/mitmproxy/script/concurrent.py
@@ -29,4 +29,7 @@ def concurrent(fn):
             "script.concurrent (%s)" % fn.__name__,
             target=run
         ).start()
-    return _concurrent
+    if "." in fn.__qualname__:
+        return staticmethod(_concurrent)
+    else:
+        return _concurrent