diff --git a/docs/interfaces/client.clientoptions.md b/docs/interfaces/client.clientoptions.md
index 88a6d2fc..afdac93d 100644
--- a/docs/interfaces/client.clientoptions.md
+++ b/docs/interfaces/client.clientoptions.md
@@ -30,7 +30,7 @@ Configuration used for the GraphQL over WebSocket client.
 
 ### connectionParams
 
-• `Optional` **connectionParams**: `Record`<string, unknown\> \| () => `Record`<string, unknown\> \| `Promise`<Record<string, unknown\>\>
+• `Optional` **connectionParams**: `Record`<string, unknown\> \| () => `undefined` \| `Record`<string, unknown\> \| `Promise`<undefined \| Record<string, unknown\>\>
 
 Optional parameters, passed through the `payload` field with the `ConnectionInit` message,
 that the client specifies when establishing a connection with the server. You can use this
diff --git a/src/client.ts b/src/client.ts
index 2275b003..fa3ba518 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -11,6 +11,7 @@ import {
   Disposable,
   Message,
   MessageType,
+  ConnectionInitMessage,
   ConnectionAckMessage,
   PingMessage,
   PongMessage,
@@ -170,8 +171,10 @@ export interface ClientOptions {
    * in the close event reason.
    */
   connectionParams?:
-    | Record<string, unknown>
-    | (() => Promise<Record<string, unknown>> | Record<string, unknown>);
+    | ConnectionInitMessage['payload']
+    | (() =>
+        | Promise<ConnectionInitMessage['payload']>
+        | ConnectionInitMessage['payload']);
   /**
    * Controls when should the connection be established.
    *