diff --git a/src/codec-components/EditCodec/CEnum.tsx b/src/codec-components/EditCodec/CEnum.tsx
index 44c4b80..9ee58bb 100644
--- a/src/codec-components/EditCodec/CEnum.tsx
+++ b/src/codec-components/EditCodec/CEnum.tsx
@@ -1,5 +1,5 @@
 import { SearchableSelect } from "@/components/Select"
-import { isEnumComplex, isEnumVoid } from "@/utils/shape"
+import { getEnumDefaultValue, isEnumComplex } from "@/utils/shape"
 import { EditEnum, NOTIN } from "@polkadot-api/react-builder"
 import { Marker } from "../common/Markers"
 import { useSubtreeFocus } from "../common/SubtreeFocus"
@@ -43,7 +43,7 @@ export const CEnum: EditEnum = ({
         <SearchableSelect
           setValue={(selected: string | null) => {
             if (selected && options.includes(selected)) {
-              const value = isEnumVoid(shape, selected) ? null : NOTIN
+              const value = getEnumDefaultValue(shape, selected)
               onValueChanged({ type: selected, value })
             }
           }}
diff --git a/src/codec-components/EditCodec/CSequence.tsx b/src/codec-components/EditCodec/CSequence.tsx
index 0d180cb..bb3f511 100644
--- a/src/codec-components/EditCodec/CSequence.tsx
+++ b/src/codec-components/EditCodec/CSequence.tsx
@@ -3,12 +3,14 @@ import { CirclePlus } from "lucide-react"
 import { twMerge as clsx } from "tailwind-merge"
 import { ListItem } from "../common/ListItem"
 import { useSubtreeFocus } from "../common/SubtreeFocus"
+import { getDefaultValue } from "@/utils"
 
 export const CSequence: EditSequence = ({
   innerComponents,
   value,
   onValueChanged,
   path,
+  shape,
 }) => {
   const focus = useSubtreeFocus()
   const sub = focus.getNextPath(path)
@@ -18,7 +20,7 @@ export const CSequence: EditSequence = ({
 
   const addItem = () => {
     const curr = value !== NOTIN ? value.slice() : []
-    curr.push(NOTIN)
+    curr.push(getDefaultValue(shape.value))
     onValueChanged([...curr])
   }
 
diff --git a/src/codec-components/EditCodec/codec-components.tsx b/src/codec-components/EditCodec/codec-components.tsx
index 8d1d20c..02d70f8 100644
--- a/src/codec-components/EditCodec/codec-components.tsx
+++ b/src/codec-components/EditCodec/codec-components.tsx
@@ -1,11 +1,11 @@
 import SliderToggle from "@/components/Toggle"
+import { getDefaultValue } from "@/utils"
 import {
   EditArray,
   EditBool,
   EditOption,
   EditResult,
   EditVoid,
-  NOTIN,
 } from "@polkadot-api/react-builder"
 import { FC, ReactNode, useState } from "react"
 import { twMerge } from "tailwind-merge"
@@ -61,7 +61,12 @@ export const CArray: EditArray = ({ innerComponents, path }) => {
   )
 }
 
-export const COption: EditOption = ({ value, inner, onValueChanged }) => {
+export const COption: EditOption = ({
+  value,
+  inner,
+  shape,
+  onValueChanged,
+}) => {
   const selected = value !== undefined
   return (
     <div>
@@ -69,7 +74,9 @@ export const COption: EditOption = ({ value, inner, onValueChanged }) => {
         <SliderToggle
           isToggled={selected}
           toggle={() =>
-            !selected ? onValueChanged(NOTIN) : onValueChanged(undefined)
+            !selected
+              ? onValueChanged(getDefaultValue(shape.value))
+              : onValueChanged(undefined)
           }
         />
         <span className="text-base">
diff --git a/src/utils/shape.ts b/src/utils/shape.ts
index bb77d94..1180792 100644
--- a/src/utils/shape.ts
+++ b/src/utils/shape.ts
@@ -1,4 +1,7 @@
 import { EnumVar, StructVar, Var } from "@polkadot-api/metadata-builders"
+import { NOTIN } from "@polkadot-api/react-builder"
+import { Enum } from "polkadot-api"
+import { mapObject } from "polkadot-api/utils"
 
 const complexTypes = new Set<Var["type"]>([
   "tuple",
@@ -40,14 +43,49 @@ export const getStructInnerType = <T extends StructVar>(
   return shape.value[key].type
 }
 
-export const isEnumVoid = <T extends EnumVar>(
+const MAX_DEPTH = 5
+export const getDefaultValue = (innerVar: Var, depth = 0): any => {
+  if (depth > MAX_DEPTH) return NOTIN
+  const nextDefault = (v: Var) => getDefaultValue(v, depth + 1)
+
+  switch (innerVar.type) {
+    case "void":
+      return null
+    case "option":
+      return undefined
+    case "sequence":
+      return []
+    case "struct":
+      return mapObject(innerVar.value, (v) => nextDefault(v))
+    case "array":
+      return new Array(innerVar.len)
+        .fill(0)
+        .map(() => nextDefault(innerVar.value))
+    case "tuple":
+      return innerVar.value.map(nextDefault)
+    case "enum": {
+      const selected = Object.entries(innerVar.value)[0]
+      return selected
+        ? Enum(
+            selected[0],
+            nextDefault(
+              selected[1].type === "lookupEntry"
+                ? selected[1].value
+                : selected[1],
+            ),
+          )
+        : NOTIN
+    }
+  }
+  return NOTIN
+}
+
+export const getEnumDefaultValue = <T extends EnumVar>(
   shape: T,
   type: keyof T["value"],
-): boolean => {
-  const innerShape = shape.value[type]
-  const innerType =
-    innerShape.type === "lookupEntry" ? innerShape.value.type : innerShape.type
-  return innerType === "void"
+) => {
+  const innerVar = getEnumInnerVar(shape, type)
+  return getDefaultValue(innerVar)
 }
 
 export const getFinalType = (shape: any, name: string) => {