diff --git a/src/utils/collection.ts b/src/utils/collection.ts
index 0ceb347e5..9576512e0 100644
--- a/src/utils/collection.ts
+++ b/src/utils/collection.ts
@@ -16,7 +16,7 @@ export class Collection<K, V> extends Map<K, V> {
     return [...this.values()];
   }
 
-  first() {
+  first(): V {
     return this.values().next().value;
   }