diff --git a/aider/coders/editblock_coder.py b/aider/coders/editblock_coder.py
index 017e40408..557e692b6 100644
--- a/aider/coders/editblock_coder.py
+++ b/aider/coders/editblock_coder.py
@@ -414,16 +414,8 @@ def find_original_update_blocks(content, fence=DEFAULT_FENCE):
 
             processed.append(cur)  # original_marker
 
-            filename = strip_filename(processed[-2].splitlines()[-1], fence)
-            try:
-                if not filename:
-                    filename = strip_filename(processed[-2].splitlines()[-2], fence)
-                if not filename:
-                    if current_filename:
-                        filename = current_filename
-                    else:
-                        raise ValueError(missing_filename_err.format(fence=fence))
-            except IndexError:
+            filename = find_filename(processed[-2].splitlines(), fence)
+            if not filename:
                 if current_filename:
                     filename = current_filename
                 else:
@@ -460,6 +452,35 @@ def find_original_update_blocks(content, fence=DEFAULT_FENCE):
         raise ValueError(f"{processed}\n^^^ Error parsing SEARCH/REPLACE block.")
 
 
+def find_filename(lines, fence):
+    """
+    Deepseek Coder v2 has been doing this:
+
+
+     ```python
+    word_count.py
+    ```
+    ```python
+    <<<<<<< SEARCH
+    ...
+
+    This is a more flexible search back for filenames.
+    """
+    # Go back through the 3 preceding lines
+    lines.reverse()
+    lines = lines[:3]
+
+    for line in lines:
+        # If we find a filename, done
+        filename = strip_filename(line, fence)
+        if filename:
+            return filename
+
+        # Only continue as long as we keep seeing fences
+        if not line.startswith(fence[0]):
+            return
+
+
 if __name__ == "__main__":
     edit = """
 Here's the change:
diff --git a/aider/models.py b/aider/models.py
index ac150d546..50548446d 100644
--- a/aider/models.py
+++ b/aider/models.py
@@ -236,7 +236,7 @@ MODEL_SETTINGS = [
         send_undo_reply=True,
     ),
     ModelSettings(
-        "openai/deepseek-chat",
+        "deepseek/deepseek-chat",
         "diff",
         use_repo_map=True,
         send_undo_reply=True,
@@ -244,7 +244,15 @@ MODEL_SETTINGS = [
         reminder_as_sys_msg=True,
     ),
     ModelSettings(
-        "deepseek/deepseek-chat",
+        "deepseek/deepseek-coder",
+        "diff",
+        use_repo_map=True,
+        send_undo_reply=True,
+        examples_as_sys_msg=True,
+        reminder_as_sys_msg=True,
+    ),
+    ModelSettings(
+        "openrouter/deepseek/deepseek-coder",
         "diff",
         use_repo_map=True,
         send_undo_reply=True,
diff --git a/aider/tests/test_editblock.py b/aider/tests/test_editblock.py
index 0c1143232..40a0d4572 100644
--- a/aider/tests/test_editblock.py
+++ b/aider/tests/test_editblock.py
@@ -398,6 +398,32 @@ Hope you like it!
             ],
         )
 
+    def test_deepseek_coder_v2_filename_mangling(self):
+        edit = """
+Here's the change:
+
+ ```python
+foo.txt
+```
+```python
+<<<<<<< SEARCH
+one
+=======
+two
+>>>>>>> REPLACE
+```
+
+Hope you like it!
+"""
+
+        edits = list(eb.find_original_update_blocks(edit))
+        self.assertEqual(
+            edits,
+            [
+                ("foo.txt", "one\n", "two\n"),
+            ],
+        )
+
 
 if __name__ == "__main__":
     unittest.main()