diff --git a/package.json b/package.json
index 3cf2f3214..068f5654e 100644
--- a/package.json
+++ b/package.json
@@ -17,6 +17,6 @@
   },
   "devDependencies": {
     "@polkadot/dev": "^0.20.2",
-    "@polkadot/ts": "^0.0.20"
+    "@polkadot/ts": "^0.0.24"
   }
 }
diff --git a/packages/util/src/ext/error.ts b/packages/util/src/ext/error.ts
index 162cbeaaf..79ead018d 100644
--- a/packages/util/src/ext/error.ts
+++ b/packages/util/src/ext/error.ts
@@ -39,7 +39,7 @@ export default class ExtError extends Error implements ExtErrorInterface {
   // @ts-ignore we are assigning it via extend
   stack: string;
 
-  constructor (message: string = '', code: number = UNKNOWN, data: any) {
+  constructor (message: string = '', code: number = UNKNOWN, data?: any) {
     super();
 
     extend(this, 'message', String(message));
diff --git a/yarn.lock b/yarn.lock
index 6bb8e2246..e4c731cc6 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -741,9 +741,9 @@
     rimraf "^2.6.2"
     typescript "^2.9.2"
 
-"@polkadot/ts@^0.0.20":
-  version "0.0.20"
-  resolved "https://registry.yarnpkg.com/@polkadot/ts/-/ts-0.0.20.tgz#a1d413e5e743a6f64acb2a8525beabc4090bb06d"
+"@polkadot/ts@^0.0.24":
+  version "0.0.24"
+  resolved "https://registry.yarnpkg.com/@polkadot/ts/-/ts-0.0.24.tgz#e771cfec096759d5b8522a9b474b0eefb95bfc45"
 
 "@types/base-x@*":
   version "1.0.29"