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/coders/base_coder.py b/aider/coders/base_coder.py
index 7def7b52d..b6c0ead61 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -48,6 +48,7 @@ class Coder:
     abs_fnames = None
     repo = None
     last_aider_commit_hash = None
+    aider_commit_hashes = set()
     aider_edited_files = None
     last_asked_for_commit_time = 0
     repo_map = None
@@ -117,6 +118,7 @@ class Coder:
                 fnames=from_coder.get_inchat_relative_files(),
                 done_messages=done_messages,
                 cur_messages=from_coder.cur_messages,
+                aider_commit_hashes=from_coder.aider_commit_hashes,
             )
 
             use_kwargs.update(update)  # override to complete the switch
@@ -226,6 +228,7 @@ class Coder:
         attribute_author=True,
         attribute_committer=True,
         attribute_commit_message=False,
+        aider_commit_hashes=None,
     ):
         if not fnames:
             fnames = []
@@ -233,6 +236,11 @@ class Coder:
         if io is None:
             io = InputOutput()
 
+        if aider_commit_hashes:
+            self.aider_commit_hashes = aider_commit_hashes
+        else:
+            self.aider_commit_hashes = set()
+
         self.chat_completion_call_hashes = []
         self.chat_completion_response_hashes = []
         self.need_commit_before_edits = set()
@@ -1454,6 +1462,7 @@ class Coder:
         if res:
             commit_hash, commit_message = res
             self.last_aider_commit_hash = commit_hash
+            self.aider_commit_hashes.add(commit_hash)
             self.last_aider_commit_message = commit_message
             if self.show_diffs:
                 self.commands.cmd_diff()
diff --git a/aider/commands.py b/aider/commands.py
index b42894e27..4c8933f7e 100644
--- a/aider/commands.py
+++ b/aider/commands.py
@@ -333,8 +333,9 @@ class Commands:
                 )
                 return
 
-        last_commit = self.coder.repo.repo.head.commit
-        if last_commit.hexsha[:7] != self.coder.last_aider_commit_hash:
+        last_commit_hash = self.coder.repo.repo.head.commit.hexsha[:7]
+        last_commit_message = self.coder.repo.repo.head.commit.message.strip()
+        if last_commit_hash not in self.coder.aider_commit_hashes:
             self.io.tool_error("The last commit was not made by aider in this chat session.")
             self.io.tool_error(
                 "You could try `/git reset --hard HEAD^` but be aware that this is a destructive"
@@ -348,9 +349,12 @@ class Commands:
         # Move the HEAD back before the latest commit
         self.coder.repo.repo.git.reset("--soft", "HEAD~1")
 
-        self.io.tool_output(
-            f"Commit `{self.coder.last_aider_commit_hash}` was reset and removed from git.\n"
-        )
+        self.io.tool_output(f"Removed: {last_commit_hash} {last_commit_message}")
+
+        # Get the current HEAD after undo
+        current_head_hash = self.coder.repo.repo.head.commit.hexsha[:7]
+        current_head_message = self.coder.repo.repo.head.commit.message.strip()
+        self.io.tool_output(f"HEAD is: {current_head_hash} {current_head_message}")
 
         if self.coder.main_model.send_undo_reply:
             return prompts.undo_command_reply
@@ -361,16 +365,17 @@ class Commands:
             self.io.tool_error("No git repository found.")
             return
 
-        if not self.coder.last_aider_commit_hash:
-            self.io.tool_error("No previous aider commit found.")
+        last_commit_hash = self.coder.repo.repo.head.commit.hexsha[:7]
+
+        if last_commit_hash not in self.coder.aider_commit_hashes:
+            self.io.tool_error(f"Last commit {last_commit_hash} was not an aider commit.")
             self.io.tool_error("You could try `/git diff` or `/git diff HEAD^`.")
             return
 
-        commits = f"{self.coder.last_aider_commit_hash}~1"
         diff = self.coder.repo.diff_commits(
             self.coder.pretty,
-            commits,
-            self.coder.last_aider_commit_hash,
+            "HEAD^",
+            "HEAD",
         )
 
         # don't use io.tool_output() because we don't want to log or further colorize
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/aider/website/HISTORY.md b/aider/website/HISTORY.md
index 03ad6a5bb..356176a09 100644
--- a/aider/website/HISTORY.md
+++ b/aider/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: