diff --git a/src/runtime/internal/dev.ts b/src/runtime/internal/dev.ts
index 1ebc722668..004ea3edaa 100644
--- a/src/runtime/internal/dev.ts
+++ b/src/runtime/internal/dev.ts
@@ -89,7 +89,7 @@ export function set_data_dev(text, data) {
 	text.data = data;
 }
 
-export function add_resize_observer_dev(node: HTMLElement, fn: (arg: any) => void, opts?: ResizeObserverOptions) {
+export function add_resize_observer_dev(node: HTMLElement, fn: () => void, opts?: ResizeObserverOptions) {
 	if ('ResizeObserver' in window) {
 		add_resize_observer(node, fn, opts);
 	} else {