diff --git a/format_ipy_cells/helpers.py b/format_ipy_cells/helpers.py
index 4735677..f28c64c 100644
--- a/format_ipy_cells/helpers.py
+++ b/format_ipy_cells/helpers.py
@@ -96,3 +96,24 @@ def delete_last_cell_if_empty(text: str) -> str:
     """
     # \Z matches only at end of string
     return re.sub(r"(?m)\s+^# %%\s*\Z", r"\n", text)
+
+
+def single_blank_line_after_doc_string(text: str) -> str:
+    """Ensure single blank line between cell delimiter and preceding module doc string.
+
+    Added to avoid clash with ruff format. Started enforcing single blank line in 0.3.0.
+
+    --- before ---
+    '''module doc string.'''
+
+
+    # %%
+    some_code = 'here'
+
+    --- after ---
+    '''module doc string.'''
+
+    # %%
+    some_code = 'here'
+    """
+    return re.sub(r'(?m)(["\']{3})\n+(# %%)', r"\1\n\n\2", text)
diff --git a/format_ipy_cells/main.py b/format_ipy_cells/main.py
index f1385be..2212ac1 100644
--- a/format_ipy_cells/main.py
+++ b/format_ipy_cells/main.py
@@ -9,6 +9,7 @@
     format_comments_after_cell_delimiters,
     remove_empty_cells,
     remove_empty_lines_starting_cell,
+    single_blank_line_after_doc_string,
 )
 
 
@@ -39,6 +40,8 @@ def fix_file(filename: str) -> int:
 
     text = delete_last_cell_if_empty(text)
 
+    text = single_blank_line_after_doc_string(text)
+
     if orig_text != text:
         print(f"Rewriting {filename}")