diff --git a/.pylintrc b/.pylintrc
index 4eeeae9..92b465c 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -7,7 +7,6 @@ disable=fixme,
         attribute-defined-outside-init,
         consider-using-generator,
         duplicate-code,
-        isinstance-second-argument-not-valid-type,
         keyword-arg-before-vararg,
         missing-function-docstring,
         missing-module-docstring,
diff --git a/src/wuttaweb/forms/schema.py b/src/wuttaweb/forms/schema.py
index ca62d8a..271bdd9 100644
--- a/src/wuttaweb/forms/schema.py
+++ b/src/wuttaweb/forms/schema.py
@@ -381,7 +381,9 @@ class ObjectRef(colander.SchemaType):
         if not value:
             return None
 
-        if isinstance(value, self.model_class):
+        if isinstance(  # pylint: disable=isinstance-second-argument-not-valid-type
+            value, self.model_class
+        ):
             return value
 
         # fetch object from DB