diff --git a/mopidy/local/commands.py b/mopidy/local/commands.py
index fb8f5368..e5290049 100644
--- a/mopidy/local/commands.py
+++ b/mopidy/local/commands.py
@@ -70,32 +70,31 @@ class ScanCommand(commands.Command):
 
         library = _get_library(args, config)
 
-        uri_path_mapping = {}
         uris_in_library = set()
         uris_to_update = set()
         uris_to_remove = set()
 
+        file_mtimes = path.find_mtimes(media_dir)
+        logger.info('Found %d files in media_dir.', len(file_mtimes))
+
         num_tracks = library.load()
         logger.info('Checking %d tracks from library.', num_tracks)
 
         for track in library.begin():
-            uri_path_mapping[track.uri] = translator.local_track_uri_to_path(
-                track.uri, media_dir)
-            try:
-                stat = os.stat(uri_path_mapping[track.uri])
-                if int(stat.st_mtime) > track.last_modified:
-                    uris_to_update.add(track.uri)
-                uris_in_library.add(track.uri)
-            except OSError:
+            abspath = translator.local_track_uri_to_path(track.uri, media_dir)
+            mtime = file_mtimes.pop(abspath, None)
+            if mtime is None:
                 logger.debug('Missing file %s', track.uri)
                 uris_to_remove.add(track.uri)
+            elif mtime > track.last_modified:
+                uris_in_library.add(track.uri)
 
         logger.info('Removing %d missing tracks.', len(uris_to_remove))
         for uri in uris_to_remove:
             library.remove(uri)
 
-        logger.info('Checking %s for unknown tracks.', media_dir)
-        for relpath in path.find_files(media_dir):
+        for abspath in file_mtimes:
+            relpath = os.path.relpath(abspath, media_dir)
             uri = translator.path_to_local_track_uri(relpath)
             file_extension = os.path.splitext(relpath)[1]
 
@@ -103,21 +102,23 @@ class ScanCommand(commands.Command):
                 logger.debug('Skipped %s: File extension excluded.', uri)
                 continue
 
-            if uri not in uris_in_library:
-                uris_to_update.add(uri)
-                uri_path_mapping[uri] = os.path.join(media_dir, relpath)
+            uris_to_update.add(uri)
 
-        logger.info('Found %d unknown tracks.', len(uris_to_update))
+        logger.info(
+            'Found %d tracks which need to be updated.', len(uris_to_update))
         logger.info('Scanning...')
 
-        uris_to_update = sorted(uris_to_update)[:args.limit]
+        uris_to_update = sorted(uris_to_update, key=lambda v: v.lower())
+        uris_to_update = uris_to_update[:args.limit]
 
         scanner = scan.Scanner(scan_timeout)
         progress = _Progress(flush_threshold, len(uris_to_update))
 
         for uri in uris_to_update:
             try:
-                data = scanner.scan(path.path_to_uri(uri_path_mapping[uri]))
+                relpath = translator.local_track_uri_to_path(uri, media_dir)
+                file_uri = path.path_to_uri(os.path.join(media_dir, relpath))
+                data = scanner.scan(file_uri)
                 track = scan.audio_data_to_track(data).copy(uri=uri)
                 library.add(track)
                 logger.debug('Added %s', track.uri)