diff --git a/src/pretix/base/models/event.py b/src/pretix/base/models/event.py
index 273300b5c..3803f1ead 100644
--- a/src/pretix/base/models/event.py
+++ b/src/pretix/base/models/event.py
@@ -445,6 +445,7 @@ class Event(EventMixin, LoggedModel):
 
         self.plugins = other.plugins
         self.is_public = other.is_public
+        self.testmode = other.testmode
         self.save()
 
         tax_map = {}