diff --git a/group-by-date.cabal b/group-by-date.cabal
--- a/group-by-date.cabal
+++ b/group-by-date.cabal
@@ -1,5 +1,5 @@
 Name:           group-by-date
-Version:        0.0
+Version:        0.0.1
 License:        BSD3
 License-File:   LICENSE
 Author:         Henning Thielemann <haskell@henning-thielemann.de>
@@ -26,9 +26,10 @@
   .
   > group-by-date -r photos | bash
   .
-  If you want a different command, say @cp@, you can call
+  If you want a different command,
+  say copying with preservation of modification time, you can call
   .
-  > group-by-date --command=cp -r photos
+  > group-by-date --command='cp -p' -r photos
   .
   Alternatively, you can run the actions immediately,
   that is, without a Bash script:
@@ -43,12 +44,12 @@
   Attention:
   Media for photographies is often formatted with FAT.
   This may yield trouble with respect to timezones.
-Tested-With:    GHC==7.8.3
+Tested-With:    GHC==7.8.4, GHC==8.2.1
 Cabal-Version:  >=1.6
 Build-Type:     Simple
 
 Source-Repository this
-  Tag:         0.0
+  Tag:         0.0.1
   Type:        darcs
   Location:    http://hub.darcs.net/thielema/group-by-date/
 
@@ -60,11 +61,10 @@
   Build-Depends:
     hsshellscript >=3.1.0 && <3.4,
     filemanip >=0.3.5 && <0.4,
-    filepath >=1.3 && <1.4,
+    filepath >=1.3 && <1.5,
     -- version for directory needed for getModificationTime returning UTCTime
-    directory >=1.2 && <1.3,
-    time >=1.4 && <1.6,
-    old-locale >=1.0 && <1.1,
+    directory >=1.2 && <1.4,
+    time >=1.5 && <1.9,
     unix-compat >=0.3 && <0.5,
     explicit-exception >=0.1 && <0.2,
     transformers >=0.2 && <0.6,
diff --git a/src/GroupByDate.hs b/src/GroupByDate.hs
--- a/src/GroupByDate.hs
+++ b/src/GroupByDate.hs
@@ -8,7 +8,6 @@
 
 import qualified Data.Time.Format as Time
 import Data.Time.Clock.POSIX (posixSecondsToUTCTime, )
-import System.Locale (defaultTimeLocale, )
 
 import Text.Printf (printf, )
 
@@ -17,13 +16,13 @@
 
 folderFromStatus :: String -> Files.FileStatus -> FilePath
 folderFromStatus fmt =
-   Time.formatTime defaultTimeLocale fmt .
+   Time.formatTime Time.defaultTimeLocale fmt .
    posixSecondsToUTCTime . realToFrac .
    Files.modificationTime
 
 folderFromPath :: String -> FilePath -> IO FilePath
 folderFromPath fmt =
-   fmap (Time.formatTime defaultTimeLocale fmt) .
+   fmap (Time.formatTime Time.defaultTimeLocale fmt) .
    Dir.getModificationTime