diff --git a/src/index.ts b/src/index.ts
index 73e1962..e4c9b35 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -444,7 +444,7 @@ function getValidCacheMap<K, V, C>(
 }
 
 // Private
-function isArrayLike(x: any): boolean {
+function isArrayLike<T>(x: any): x is ArrayLike<T> {
   return (
     typeof x === 'object' &&
     x !== null &&