diff --git a/packages/checkout/sdk/src/postMessageHandler/postMessageHandler.ts b/packages/checkout/sdk/src/postMessageHandler/postMessageHandler.ts
index 148efe6c1c..0142aa6509 100644
--- a/packages/checkout/sdk/src/postMessageHandler/postMessageHandler.ts
+++ b/packages/checkout/sdk/src/postMessageHandler/postMessageHandler.ts
@@ -6,12 +6,21 @@ export type PostMessageHandlerConfiguration = {
 // todo put these in a types file
 export enum PostMessageHandlerEventType {
   PROVIDER_RELAY = 'IMTBL_PROVIDER_RELAY',
+  EIP_6963_EVENT = 'IMTBL_EIP_6963_EVENT',
   WIDGET_EVENT = 'IMTBL_CHECKOUT_WIDGET_EVENT',
 }
 
+export type PostMessageProviderRelayData = any;
+
+export type PostMessageEIP6963Data = any;
+
+export type PostMessagePayaload =
+  | PostMessageProviderRelayData
+  | PostMessageEIP6963Data;
+
 export type PostMessageData = {
   type: PostMessageHandlerEventType;
-  payload: any;
+  payload: PostMessagePayaload;
 };
 
 export interface MinimalEventSourceInterface {