diff --git a/phototrie/datename.py b/phototrie/datename.py
index 89b1457..cded8ed 100644
--- a/phototrie/datename.py
+++ b/phototrie/datename.py
@@ -4,6 +4,8 @@ import sys
 import exifread
 import re
 
+from exifread.classes import IfdTag
+
 DATETIME_KEY = "Image DateTime"
 DATETIME_PATTERN = re.compile(r"^(\d{4}):(\d{2}):(\d{2}) (\d{2}):(\d{2}):(\d{2})$")
 
@@ -18,11 +20,9 @@ def get_new_name(filename, date_matches):
 
     while True:
         if suffix == 0:
-            target = (
-                f"{dirn}/{year}-{month}-{date}_{hour}:{second}:{minute}.{extension}"
-            )
+            target = f"{dirn}/{year}-{month}-{date}_{hour}:{second}:{minute}{extension}"
         else:
-            target = f"{dirn}/{year}-{month}-{date}_{hour}:{second}:{minute}_{suffix}.{extension}"
+            target = f"{dirn}/{year}-{month}-{date}_{hour}:{second}:{minute}_{suffix}{extension}"
 
         if not os.path.exists(target):
             return target
@@ -59,7 +59,8 @@ def cli():
             print(f"No datetime tag found for: {filename}", file=sys.stderr)
             continue
 
-        match = DATETIME_PATTERN.match(tags[DATETIME_KEY])
+        ifd_tag: IfdTag = tags[DATETIME_KEY]
+        match = DATETIME_PATTERN.match(ifd_tag.values)
         if match is None:
             print(
                 f"Invalid datetime tag ({tags[DATETIME_KEY]!r}) found for: {filename}",