diff --git a/packages/utils/src/loader/types.ts b/packages/utils/src/loader/types.ts
index 1757116..7c8ce9b 100644
--- a/packages/utils/src/loader/types.ts
+++ b/packages/utils/src/loader/types.ts
@@ -156,7 +156,7 @@ export type IconifyLoaderOptions = {
 	 */
 	autoInstall?: boolean;
 
-	customInstall?: Function;
+	customInstall?: (name: string) => Promise<void | undefined>;
 	/**
 	 * The additional icon properties applied to the svg.
 	 *