diff --git a/bertopic/_bertopic.py b/bertopic/_bertopic.py
index 171136df..ea11fefc 100644
--- a/bertopic/_bertopic.py
+++ b/bertopic/_bertopic.py
@@ -4495,11 +4495,11 @@ def _auto_reduce_topics(self, documents: pd.DataFrame, use_ctfidf: bool = False)
         for key, val in sorted(mapped_topics.items()):
             mappings[val].append(key)
         mappings = {
-            topic_from: {
-                "topics_to": topics_to,
-                "topic_sizes": [self.topic_sizes_[topic] for topic in topics_to],
+            topic_to: {
+                "topics_from": topics_from,
+                "topic_sizes": [self.topic_sizes_[topic] for topic in topics_from],
             }
-            for topic_from, topics_to in mappings.items()
+            for topic_to, topics_from in mappings.items()
         }
 
         # Update documents and topics
diff --git a/tests/conftest.py b/tests/conftest.py
index 3d8d49db..fd278b0f 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -114,7 +114,7 @@ def representation_topic_model(documents, document_embeddings, embedding_model):
 @pytest.fixture(scope="session")
 def reduced_topic_model(custom_topic_model, documents):
     model = copy.deepcopy(custom_topic_model)
-    model.reduce_topics(documents, nr_topics=12)
+    model.reduce_topics(documents, nr_topics="auto")
     return model