diff --git a/units/wikis.py b/units/wikis.py
index 7f70c2f11d..86628c2015 100644
--- a/units/wikis.py
+++ b/units/wikis.py
@@ -29,7 +29,10 @@ class WikiArticle(BaseModel):
     wiki: WikiInfo
 
     def __eq__(self, other):
-        return self.url == other.url
+        if isinstance(other, WikiArticle):
+            return self.url == other.url
+        else:
+            return NotImplemented
 
     def __hash__(self) -> int:
         return hash(self.url)