diff --git a/src/graphql/schema/buildMutationInputType.ts b/src/graphql/schema/buildMutationInputType.ts
index 9b121880bb..844031ac24 100644
--- a/src/graphql/schema/buildMutationInputType.ts
+++ b/src/graphql/schema/buildMutationInputType.ts
@@ -135,7 +135,7 @@ function buildMutationInputType(name: string, fields: Field[], parentName: strin
         ];
       }
 
-      return null;
+      return acc;
     }, []),
   };