diff --git a/README.md b/README.md
index d9db369..be6173d 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,9 @@ This script:
    with a plain stream copy) and concatenates everything into one file.
 5. Carries over the original container metadata (GPS, device info, creation
    time, Live Photo identifiers) from one of the source clips.
+6. Sets the output file's filesystem modification time to match that same
+   capture time — some tools (e.g. Synology Photos, for videos) sort/date
+   by file mtime instead of parsing embedded metadata.
 
 Audio stays uncompressed PCM throughout, so it never loses quality. Video
 quality defaults to a bitrate slightly above the source clips' own bitrate
diff --git a/concat_live_clips.py b/concat_live_clips.py
index 1cc481b..92374a4 100755
--- a/concat_live_clips.py
+++ b/concat_live_clips.py
@@ -28,6 +28,7 @@ Requirements:
       detects clip overlap): pip install --user numpy
 """
 import argparse
+import os
 import re
 import subprocess
 import sys
@@ -365,6 +366,17 @@ def main():
 
     print(f"Encoding seamless, deduplicated output -> {output}", file=sys.stderr)
     subprocess.run(cmd, check=True)
+
+    creation_dt = fetch_creation_time(clips[args.metadata_from])
+    if creation_dt is not None:
+        ts = creation_dt.timestamp()
+        os.utime(output, (ts, ts))
+        print(f"Set file mtime to {creation_dt.isoformat()} (matches embedded metadata, "
+              f"so apps that key off filesystem time instead of parsing video metadata "
+              f"still sort/date it correctly)", file=sys.stderr)
+    else:
+        print("warning: couldn't determine source creation time; leaving file mtime as-is", file=sys.stderr)
+
     print(f"Done: {output}", file=sys.stderr)