diff --git a/.changeset/shy-monkeys-raise.md b/.changeset/shy-monkeys-raise.md
new file mode 100644
index 000000000000..e19249fb0032
--- /dev/null
+++ b/.changeset/shy-monkeys-raise.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Update typings of `event.platform` to be possibly undefined
diff --git a/packages/kit/types/index.d.ts b/packages/kit/types/index.d.ts
index d41d2050298d..2944b989c348 100644
--- a/packages/kit/types/index.d.ts
+++ b/packages/kit/types/index.d.ts
@@ -865,7 +865,7 @@ export interface RequestEvent<
 	/**
 	 * Additional data made available through the adapter.
 	 */
-	platform: Readonly<App.Platform>;
+	platform: Readonly<App.Platform> | undefined;
 	/**
 	 * The original request object
 	 */