diff --git a/tiramisu/config.py b/tiramisu/config.py
index 00d31d8..bb284d0 100644
--- a/tiramisu/config.py
+++ b/tiramisu/config.py
@@ -739,4 +739,4 @@ class MetaConfig(GroupConfig):
 
 def mandatory_warnings(config):
     #only for retro-compatibility
-    config.cfgimpl_get_values().mandatory_warnings()
+    return config.cfgimpl_get_values().mandatory_warnings()