diff --git a/HISTORY.md b/HISTORY.md
index 3f5fffda1..8f994ff77 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -1,6 +1,10 @@
 
 # Release history
 
+### main branch
+
+- Allow multiple use of `/undo`.
+
 ### Aider v0.42.0
 
 - Performance release:
diff --git a/aider/tests/test_commands.py b/aider/tests/test_commands.py
index 262262f39..740cb147d 100644
--- a/aider/tests/test_commands.py
+++ b/aider/tests/test_commands.py
@@ -536,7 +536,7 @@ class TestCommands(TestCase):
 
             # Store the commit hash
             last_commit_hash = repo.head.commit.hexsha[:7]
-            coder.last_aider_commit_hash = last_commit_hash
+            coder.aider_commit_hashes.add(last_commit_hash)
 
             file_path.write_text("dirty content")
 
diff --git a/website/HISTORY.md b/website/HISTORY.md
index 03ad6a5bb..356176a09 100644
--- a/website/HISTORY.md
+++ b/website/HISTORY.md
@@ -12,6 +12,10 @@ cog.out(text)
 
 # Release history
 
+### main branch
+
+- Allow multiple use of `/undo`.
+
 ### Aider v0.42.0
 
 - Performance release: