diff --git a/aider/coders/editblock_coder.py b/aider/coders/editblock_coder.py
index c96423dfb..b63f577a2 100644
--- a/aider/coders/editblock_coder.py
+++ b/aider/coders/editblock_coder.py
@@ -95,7 +95,7 @@ def replace_part_with_missing_leading_whitespace(whole, part, replace):
     # If all lines in the part start with whitespace, then honor it.
     # But GPT often outdents the part and replace blocks completely,
     # thereby discarding the actual leading whitespace in the file.
-    if all((len(pline) > 0 and pline[0].isspace()) for pline in part_lines):
+    if all((not pline or pline[0].isspace()) for pline in part_lines):
         return
 
     for i in range(len(whole_lines) - len(part_lines) + 1):
diff --git a/tests/test_editblock.py b/tests/test_editblock.py
index 1c140223b..68cc118b5 100644
--- a/tests/test_editblock.py
+++ b/tests/test_editblock.py
@@ -209,6 +209,20 @@ These changes replace the `subprocess.run` patches with `subprocess.check_output
         result = eb.replace_part_with_missing_leading_whitespace(whole, part, replace)
         self.assertEqual(result, expected_output)
 
+    def test_replace_part_with_missing_leading_whitespace_including_blank_lines(self):
+        """
+        The part has leading whitespace on all lines, so should be ignored.
+        But it has a *blank* line with no whitespace at all, which was causing a
+        bug per issue #25. Test case to repro and confirm fix.
+        """
+        whole = "    line1\n    line2\n    line3\n"
+        part = "\n  line1\n  line2"
+        replace = "new_line1\nnew_line2"
+        expected_output = None
+
+        result = utils.replace_part_with_missing_leading_whitespace(whole, part, replace)
+        self.assertEqual(result, expected_output)
+
 
 if __name__ == "__main__":
     unittest.main()