diff --git a/src/rustint/core.clj b/src/rustint/core.clj
index b5aa200..d7d037b 100644
--- a/src/rustint/core.clj
+++ b/src/rustint/core.clj
@@ -2074,7 +2074,8 @@
 (defn in?
   "true if coll contains elm"
   [coll elm]
-  (some #(= elm %) coll))
+  (boolean (some #(= elm %) coll))
+)
 
 (defn ya-declarado-localmente? [ident ctx]
   (let [inicio_scope_local (last (get ctx 0)),