diff --git a/scripts-available/CDB_Groups.sql b/scripts-available/CDB_Groups.sql
index 00cc8c7..d87c2f3 100644
--- a/scripts-available/CDB_Groups.sql
+++ b/scripts-available/CDB_Groups.sql
@@ -118,7 +118,7 @@ FUNCTION cartodb._CDB_User_RoleFromUsername(username text)
 DECLARE
   user_role TEXT;
 BEGIN
-  EXECUTE 'SELECT SCHEMA_OWNER FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_NAME = ''' || username || ''' LIMIT 1' INTO user_role;
+  EXECUTE 'SELECT SCHEMA_OWNER FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_NAME = $1 LIMIT 1' INTO user_role USING username;
   RETURN user_role;
 END
 $$ LANGUAGE PLPGSQL;