diff --git a/pgp/plugin.py b/pgp/plugin.py
index 6c8bb3b..df43f76 100644
--- a/pgp/plugin.py
+++ b/pgp/plugin.py
@@ -77,6 +77,7 @@ class PGPPlugin(GajimPlugin):
         self.description = _('PGP encryption as per XEP-0027')
         if ERROR_MSG:
             self.activatable = False
+            self.config_dialog = None
             self.available_text = ERROR_MSG
             return