diff --git a/histd.py b/histd.py
index d2dcdff..abfb3ca 100755
--- a/histd.py
+++ b/histd.py
@@ -33,8 +33,8 @@ def edit_note(base_dir: str, note_date: date):
     workdir = os.path.join(base_dir, year, month)
     os.makedirs(workdir, exist_ok=True)
 
-    # Open file (base_dir/year/month/day.txt) with default editor
-    filename = f'{note_date.day:02}.txt'
+    # Open file (base_dir/year/month/day.md) with default editor
+    filename = f'{note_date.day:02}.md'
     path_to_file = os.path.join(workdir, filename)
     editor = os.environ.get('EDITOR', 'nano')
     try:
diff --git a/readme.md b/readme.md
index 8dc61c8..f63314f 100644
--- a/readme.md
+++ b/readme.md
@@ -11,8 +11,8 @@ tree ~/.local/share/histd
 # /home/user/.local/share/histd
 # └── 2022
 #     └── 08
-#         ├── 18.txt
-#         └── 19.txt
+#         ├── 18.md
+#         └── 19.md
 ```
 
 ## Usage