diff --git a/src/metabase/models/interface.clj b/src/metabase/models/interface.clj
index 1fa459999fd563fe9f61465e0517cc7a728fa13c..386a893d3fe820c417c2dc714c9dc72c9905915f 100644
--- a/src/metabase/models/interface.clj
+++ b/src/metabase/models/interface.clj
@@ -5,10 +5,8 @@
     "Called on all objects being written out by the API. Default implementations return THIS as-is, but models can provide
      custom methods to strip sensitive data, from non-admins, etc."))
 
-(extend-protocol IModelInstanceApiSerialize
-  Object
-  (api-serialize [this]
-    this)
-  nil
-  (api-serialize [_]
-    nil))
+(extend Object
+  IModelInstanceApiSerialize {:api-serialize identity})
+
+(extend nil
+  IModelInstanceApiSerialize {:api-serialize identity})