diff --git a/packages/types/src/interfaces/system/definitions.ts b/packages/types/src/interfaces/system/definitions.ts
index b6aa7e8c72..88650b3237 100644
--- a/packages/types/src/interfaces/system/definitions.ts
+++ b/packages/types/src/interfaces/system/definitions.ts
@@ -395,7 +395,7 @@ export default {
     },
     WeightPerClass: {
       baseExtrinsic: 'Weight',
-      maxExtrinsic: 'Weight',
+      maxExtrinsic: 'Option<Weight>',
       maxTotal: 'Option<Weight>',
       reserved: 'Option<Weight>'
     }