diff --git a/src/event-handler/index.ts b/src/event-handler/index.ts
index 10d6e7ab..f17bedd7 100644
--- a/src/event-handler/index.ts
+++ b/src/event-handler/index.ts
@@ -20,7 +20,13 @@ interface EventHandler<TTransformed> {
     event: E | E[],
     callback: HandlerFunction<E, TTransformed>,
   ): void;
-  onAny(handler: (event: EmitterWebhookEvent & TTransformed) => any): void;
+  onAny(
+    handler: (
+      event: TTransformed extends unknown
+        ? EmitterWebhookEvent
+        : EmitterWebhookEvent & TTransformed,
+    ) => any,
+  ): void;
   onError(
     handler: (event: WebhookEventHandlerError<TTransformed>) => any,
   ): void;
diff --git a/src/event-handler/on.ts b/src/event-handler/on.ts
index 7d377200..f5c4e400 100644
--- a/src/event-handler/on.ts
+++ b/src/event-handler/on.ts
@@ -51,7 +51,11 @@ export function receiverOn(
 
 export function receiverOnAny<TTransformed>(
   state: State,
-  handler: (event: EmitterWebhookEvent & TTransformed) => any,
+  handler: (
+    event: TTransformed extends unknown
+      ? EmitterWebhookEvent
+      : EmitterWebhookEvent & TTransformed,
+  ) => any,
 ) {
   handleEventHandlers(state, "*", handler);
 }
diff --git a/src/index.ts b/src/index.ts
index 2d12e6f1..5dc8d91b 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -26,7 +26,11 @@ class Webhooks<TTransformed = unknown> {
     callback: HandlerFunction<E, TTransformed>,
   ) => void;
   public onAny: (
-    callback: (event: EmitterWebhookEvent & TTransformed) => any,
+    callback: (
+      event: TTransformed extends unknown
+        ? EmitterWebhookEvent
+        : EmitterWebhookEvent & TTransformed,
+    ) => any,
   ) => void;
   public onError: (
     callback: (event: WebhookEventHandlerError<TTransformed>) => any,
diff --git a/src/types.ts b/src/types.ts
index d898ad12..e64b07ea 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -64,7 +64,9 @@ export type WebhookError = Error & Partial<RequestError>;
 // todo: rename to "EmitterErrorEvent"
 export interface WebhookEventHandlerError<TTransformed = unknown>
   extends AggregateError<WebhookError> {
-  event: EmitterWebhookEvent & TTransformed;
+  event: TTransformed extends unknown
+    ? EmitterWebhookEvent
+    : EmitterWebhookEvent & TTransformed;
 }
 
 /**