diff --git a/src/runtime/internal/utils.ts b/src/runtime/internal/utils.ts
index 26055c2868..b1c27a355d 100644
--- a/src/runtime/internal/utils.ts
+++ b/src/runtime/internal/utils.ts
@@ -192,5 +192,5 @@ export function action_destroyer(action_result) {
 
 export function split_css_unit(value: number | string): [number, string] {
 	const split = typeof value === 'string' && value.match(/^\s*(-?[\d.]+)([^\s]*)\s*$/);
-	return split ? [parseFloat(split[1]), split[2] || 'px'] : [value, 'px'];
+	return split ? [parseFloat(split[1]), split[2] || 'px'] : [value as number, 'px'];
 }