diff --git a/markdown_fix_freeplane/markdown_fix_freeplane.py b/markdown_fix_freeplane/markdown_fix_freeplane.py
index b6edba5..cf208b1 100644
--- a/markdown_fix_freeplane/markdown_fix_freeplane.py
+++ b/markdown_fix_freeplane/markdown_fix_freeplane.py
@@ -7,16 +7,15 @@ License:
     Copyright (c) 2024 François Pelletier
 """
 
-
 import sys
 
-from markdown_fix_freeplane.markdown_utils import replace_title_with_list
+from markdown_utils import replace_title_with_list
 
 
 # %% main function
 
 
-def __main__():
+def main():
     """Run the script.
 
     Args:
@@ -27,11 +26,19 @@ def __main__():
     ---
 
     Examples:
-        >>> __main__()
+        >>> main()
     ---
 
     """
+    if len(sys.argv) < 2:
+        print("Usage: python markdown_to_list.py <file>")
+        sys.exit(1)
     # read file passed as argument
     with open(sys.argv[1], 'r') as my_file:
         text = my_file.read()
-    return replace_title_with_list(text)
+    print(replace_title_with_list(text))
+
+
+if __name__ == '__main__':
+    main()
+
diff --git a/markdown_fix_freeplane/markdown_utils.py b/markdown_fix_freeplane/markdown_utils.py
index 3c57281..8054f0c 100644
--- a/markdown_fix_freeplane/markdown_utils.py
+++ b/markdown_fix_freeplane/markdown_utils.py
@@ -36,6 +36,8 @@ def replace_title_with_list(text: str) -> str:
     pattern = r'^#+'
     matches = re.findall(pattern, text, re.MULTILINE)
     for match in matches:
-        nb_hashtag = len(match)-1
-        text = re.sub(match, '  ' * nb_hashtag+'-', text, count=1)
+        nb_hashtag = len(match)
+        if nb_hashtag > 1:
+            text = re.sub(match, '  ' * (nb_hashtag-1)+'-', text, count=1)
+    text = re.sub('\n\n', '\n', text)
     return text