diff --git a/src/types.ts b/src/types.ts
index 8a3e7e5..b634bd6 100755
--- a/src/types.ts
+++ b/src/types.ts
@@ -497,9 +497,9 @@ export type FilterDeletedEventCallback = (event: FilterDeletedEvent) => void;
 /**
  * A type for connection callback functions (blockchain event handler).
  */
-export type ConnectionCallback = (webSocket) => void;
+export type ConnectionCallback = (webSocket: any) => void;
 
 /**
  * A type for disconnection callback functions (blockchain event handler).
  */
-export type DisconnectionCallback = (webSocket) => void;
+export type DisconnectionCallback = (webSocket: any) => void;