diff --git a/packages/providers/src.ts/websocket-provider.ts b/packages/providers/src.ts/websocket-provider.ts
index e8b9cd868c..b720549b17 100644
--- a/packages/providers/src.ts/websocket-provider.ts
+++ b/packages/providers/src.ts/websocket-provider.ts
@@ -40,9 +40,9 @@ export type Subscription = {
 };
 
 export interface WebSocketLike {
-    onopen: (...args: Array<any>) => any;
-    onmessage: (...args: Array<any>) => any;
-    onerror: (...args: Array<any>) => any;
+    onopen: ((...args: Array<any>) => any) | null;
+    onmessage: ((...args: Array<any>) => any) | null;
+    onerror: ((...args: Array<any>) => any) | null;
 
     readyState: number;