diff --git a/src/rustint/core.clj b/src/rustint/core.clj
index 319c54b..eab9352 100644
--- a/src/rustint/core.clj
+++ b/src/rustint/core.clj
@@ -2279,7 +2279,7 @@
   (and
     (symbol?  arg)
     (not (palabra-reservada? arg))
-    (not (nil? (re-matches #"_?[a-zA-Z][a-zA-Z0-9]*" (name arg))))
+    (not (nil? (re-matches #"_?[a-zA-Z][a-zA-Z0-9_]*" (name arg))))
   )
 )