diff --git a/src/codec-components/LookupTypeEdit/LookupTypeEdit.tsx b/src/codec-components/LookupTypeEdit/LookupTypeEdit.tsx
index a980078..930059e 100644
--- a/src/codec-components/LookupTypeEdit/LookupTypeEdit.tsx
+++ b/src/codec-components/LookupTypeEdit/LookupTypeEdit.tsx
@@ -4,6 +4,7 @@ import { byteArraysAreEqual } from "@/utils/byteArray"
 import {
   CodecComponentType,
   CodecComponentValue,
+  NOTIN,
 } from "@polkadot-api/react-builder"
 import { state, useStateObservable } from "@react-rxjs/core"
 import { Codec } from "polkadot-api"
@@ -142,6 +143,7 @@ const useCodecProps = (
     if (!codec) return
     const encodedValue = (() => {
       if (componentValue.value.encoded) return componentValue.value.encoded
+      if (detectNotin(componentValue.value.decoded)) return null
       try {
         return codec.enc(componentValue.value.decoded)
       } catch (_) {
@@ -224,3 +226,9 @@ const useCodecProps = (
       }),
   }
 }
+const detectNotin: <T>(x: T) => boolean = (x) => {
+  if (x === NOTIN) return true
+  return x != null && typeof x === "object"
+    ? Object.values(x).some(detectNotin)
+    : false
+}
diff --git a/src/utils/shape.ts b/src/utils/shape.ts
index 1180792..b57fa14 100644
--- a/src/utils/shape.ts
+++ b/src/utils/shape.ts
@@ -58,9 +58,10 @@ export const getDefaultValue = (innerVar: Var, depth = 0): any => {
     case "struct":
       return mapObject(innerVar.value, (v) => nextDefault(v))
     case "array":
-      return new Array(innerVar.len)
-        .fill(0)
-        .map(() => nextDefault(innerVar.value))
+      return innerVar.value.type === "primitive" &&
+        innerVar.value.value === "u8"
+        ? NOTIN
+        : new Array(innerVar.len).fill(0).map(() => nextDefault(innerVar.value))
     case "tuple":
       return innerVar.value.map(nextDefault)
     case "enum": {