diff --git a/lib/util/runtime.js b/lib/util/runtime.js
index 69763d15ad3..616b47d67d8 100644
--- a/lib/util/runtime.js
+++ b/lib/util/runtime.js
@@ -390,6 +390,7 @@ const subtractRuntime = (a, b) => {
 			}
 			const set = new SortableSet(a);
 			set.delete(b);
+			return set;
 		} else {
 			const set = new SortableSet();
 			for (const item of a) {