diff --git a/paramecio/cromosoma/webmodel.py b/paramecio/cromosoma/webmodel.py
index 3799826..f8ba927 100644
--- a/paramecio/cromosoma/webmodel.py
+++ b/paramecio/cromosoma/webmodel.py
@@ -858,7 +858,7 @@ class WebModel:
     def check_in_list_str(self, field, in_list):
         
         for x in range(0, len(in_list)):
-            in_list[x]=self.fields[field].check(in_list[x])
+            in_list[x]=str(self.fields[field].check(in_list[x]))
                 
         return '("'+'", "'.join(in_list)+'")'