diff --git a/code_generation/rules.py b/code_generation/rules.py
index 0a0e5cfe..da1ed5dc 100644
--- a/code_generation/rules.py
+++ b/code_generation/rules.py
@@ -391,7 +391,7 @@ def update_outputs(self, outputs_to_be_updated: QuantitiesStore) -> None:
                             )
                             outputs_to_be_updated[scope].remove(removed_output)
                     for added_output in added_outputs[scope]:
-                        if added_output in outputs_to_be_updated[scope]:
+                        if added_output not in outputs_to_be_updated[scope]:
                             log.debug(
                                 "ReplaceProducer: Adding {} from outputs in scope {}".format(
                                     added_output, scope