diff --git a/osc/commandline.py b/osc/commandline.py
index c31d2e14..ff6425ee 100644
--- a/osc/commandline.py
+++ b/osc/commandline.py
@@ -7984,9 +7984,10 @@ Please submit there instead, or use --nodevelproject to force direct submission.
                     mod.__dict__.update(globals())
                     for name in dir(mod):
                         func = getattr(mod, name)
-                        # add all functions to the class (filtering only
-                        # methods which start with "do_" breaks the old behavior)
-                        if inspect.isfunction(func):
+                        # add all functions (which are defined in the imported module)
+                        # to the class (filtering only methods which start with "do_"
+                        # breaks the old behavior)
+                        if inspect.isfunction(func) and inspect.getmodule(func) == mod:
                             setattr(self.__class__, name, func)
                 except SyntaxError as e:
                     if (os.environ.get('OSC_PLUGIN_FAIL_IGNORE')):