diff --git a/Annex/MetaData.hs b/Annex/MetaData.hs
index f14db0a3ee..6280e8c810 100644
--- a/Annex/MetaData.hs
+++ b/Annex/MetaData.hs
@@ -22,7 +22,6 @@ import Annex.CatFile
 import Utility.Glob
 
 import qualified Data.Set as S
-import qualified Data.Map as M
 import Data.Time.Calendar
 import Data.Time.Clock
 import Data.Time.Clock.POSIX
@@ -41,28 +40,43 @@ genMetaData :: Key -> FilePath -> FileStatus -> Annex ()
 genMetaData key file status = do
 	catKeyFileHEAD file >>= \case
 		Nothing -> noop
-		Just oldkey -> 
-			whenM (copyMetaData oldkey key)
+		Just oldkey ->
+			-- Have to copy first, before adding any
+			-- more metadata, because copyMetaData does not
+			-- preserve any metadata already on key.
+			whenM (copyMetaData oldkey key <&&> (not <$> onlydatemeta oldkey)) $
 				warncopied
 	whenM (annexGenMetaData <$> Annex.getGitConfig) $ do
-		curr <- getCurrentMetaData key
-		addMetaData key (dateMetaData mtime curr)
+		old <- getCurrentMetaData key
+		addMetaData key (dateMetaData mtime old)
   where
 	mtime = posixSecondsToUTCTime $ realToFrac $ modificationTime status
 	warncopied = warning $ 
 		"Copied metadata from old version of " ++ file ++ " to new version. " ++ 
 		"If you don't want this copied metadata, run: git annex metadata --remove-all " ++ file
+	-- If the only fields copied were date metadata, and they'll
+	-- be overwritten with the current mtime, no need to warn about
+	-- copying.
+	onlydatemeta oldkey = ifM (annexGenMetaData <$> Annex.getGitConfig)
+		( null . filter (not . isDateMetaField . fst) . fromMetaData 
+			<$> getCurrentMetaData oldkey
+		, return False
+		)
 
 {- Generates metadata for a file's date stamp.
- - Does not overwrite any existing metadata values. -}
+ -
+ - Any date fields in the old metadata will be overwritten.
+ - 
+ - Note that the returned MetaData does not contain all the input MetaData,
+ - only changes to add the date fields. -}
 dateMetaData :: UTCTime -> MetaData -> MetaData
-dateMetaData mtime old = MetaData $ M.fromList $ filter isnew
-	[ (yearMetaField, S.singleton $ toMetaValue $ show y)
-	, (monthMetaField, S.singleton $ toMetaValue $ show m)
-	, (dayMetaField, S.singleton $ toMetaValue $ show d)
-	]
+dateMetaData mtime old = modMeta old $
+	(SetMeta yearMetaField $ S.singleton $ toMetaValue $ show y)
+		`ComposeModMeta`
+	(SetMeta monthMetaField $ S.singleton $ toMetaValue $ show m)
+		`ComposeModMeta`
+	(SetMeta dayMetaField $ S.singleton $ toMetaValue $ show d)
   where
-	isnew (f, _) = S.null (currentMetaDataValues f old)
 	(y, m, d) = toGregorian $ utctDay mtime
 
 {- Parses field=value, field+=value, field-=value, field?=value -}
diff --git a/Annex/MetaData/StandardFields.hs b/Annex/MetaData/StandardFields.hs
index b9ea47e2f6..b2a3f34423 100644
--- a/Annex/MetaData/StandardFields.hs
+++ b/Annex/MetaData/StandardFields.hs
@@ -10,6 +10,7 @@ module Annex.MetaData.StandardFields (
 	yearMetaField,
 	monthMetaField,
 	dayMetaField,
+	isDateMetaField,
 	lastChangedField,
 	mkLastChangedField,
 	isLastChangedField
@@ -31,6 +32,12 @@ monthMetaField = mkMetaFieldUnchecked "month"
 dayMetaField :: MetaField
 dayMetaField = mkMetaFieldUnchecked "day"
 
+isDateMetaField :: MetaField -> Bool
+isDateMetaField yearMetaField = True
+isDateMetaField monthMetaField = True
+isDateMetaField datMetaField = True
+isDateMetaField _ = False
+
 lastChangedField :: MetaField
 lastChangedField = mkMetaFieldUnchecked lastchanged
 
diff --git a/CHANGELOG b/CHANGELOG
index 7c6d2eb84f..cf43c0f0c8 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -8,6 +8,9 @@ git-annex (6.20180317) UNRELEASED; urgency=medium
     to configure transfer retries.
   * Also do forward retrying in cases where no exception is thrown,
     but the transfer failed.
+  * When adding a new version of a file, and annex.genmetadata is enabled,
+    don't copy the data metadata from the old version of the file,
+    instead use the mtime of the file.
 
  -- Joey Hess <id@joeyh.name>  Mon, 19 Mar 2018 23:13:59 -0400
 
diff --git a/Types/MetaData.hs b/Types/MetaData.hs
index bc27c345f4..279aacbb84 100644
--- a/Types/MetaData.hs
+++ b/Types/MetaData.hs
@@ -252,13 +252,15 @@ data ModMeta
 	= AddMeta MetaField MetaValue
 	| DelMeta MetaField (Maybe MetaValue)
 	-- ^ delete value of a field. With Just, only that specific value
-	-- is deleted; with Nothing, all current values are deleted.a
+	-- is deleted; with Nothing, all current values are deleted.
 	| DelAllMeta
 	-- ^ delete all currently set metadata
 	| SetMeta MetaField (S.Set MetaValue)
 	-- ^ removes any existing values
 	| MaybeSetMeta MetaField MetaValue
 	-- ^ set when field has no existing value
+	| ComposeModMeta ModMeta ModMeta
+	-- ^ composing multiple modifications
 	deriving (Show)
 
 {- Applies a ModMeta, generating the new MetaData.
@@ -279,6 +281,7 @@ modMeta m (SetMeta f s) = updateMetaData' f s $
 modMeta m (MaybeSetMeta f v)
 	| S.null (currentMetaDataValues f m) = updateMetaData f v emptyMetaData
 	| otherwise = emptyMetaData
+modMeta m (ComposeModMeta a b) = unionMetaData (modMeta m a) (modMeta m b)
 
 {- Avoid putting too many fields in the map; extremely large maps make
  - the seriaization test slow due to the sheer amount of data.
diff --git a/doc/bugs/if_annex.genmetadata_is_true__44___modification_metadata_is_imported_from_older_file_versions_after_unlock+add.mdwn b/doc/bugs/if_annex.genmetadata_is_true__44___modification_metadata_is_imported_from_older_file_versions_after_unlock+add.mdwn
index efd4ad492b..f8a77f32dc 100644
--- a/doc/bugs/if_annex.genmetadata_is_true__44___modification_metadata_is_imported_from_older_file_versions_after_unlock+add.mdwn
+++ b/doc/bugs/if_annex.genmetadata_is_true__44___modification_metadata_is_imported_from_older_file_versions_after_unlock+add.mdwn
@@ -20,3 +20,4 @@ output: `Copied metadata from old version of bar to new version. If you don't wa
 ### What version of git-annex are you using? On what operating system?
 6.20180227, various Linuxes.
 
+> [[fixed|done]] --[[Joey]]
diff --git a/doc/bugs/if_annex.genmetadata_is_true__44___modification_metadata_is_imported_from_older_file_versions_after_unlock+add/comment_1_b215c8ce0f2094a116672572951b19fc._comment b/doc/bugs/if_annex.genmetadata_is_true__44___modification_metadata_is_imported_from_older_file_versions_after_unlock+add/comment_1_b215c8ce0f2094a116672572951b19fc._comment
new file mode 100644
index 0000000000..d598c7afcb
--- /dev/null
+++ b/doc/bugs/if_annex.genmetadata_is_true__44___modification_metadata_is_imported_from_older_file_versions_after_unlock+add/comment_1_b215c8ce0f2094a116672572951b19fc._comment
@@ -0,0 +1,25 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 1"""
+ date="2018-04-04T16:51:36Z"
+ content="""
+This happens in Annex.MetaData.genMetaData. First it copies
+metadata from the oldkey to the new key. Then it
+calls addMetaData on the dateMetaData of the file's mtime.
+
+In dateMetaData, there's a `filter isnew`, which makes
+it filter out any of the date fields that already exist
+in the metadata of the new key.
+
+This was done intentionally, see 
+[[!commit 8d5158fa3151be4c7fc698b96ed887b43ac48769]]
+But that's lacking an explanation of why it was done.
+
+Note that dateMetaData is also used in Command.ImportFeed
+to convert a itempubdate into year and month metadata.
+But changing its behavior to override old dates 
+would not change that code path.
+
+So, I don't see a problem with making this change, and have gone ahead and
+done it.
+"""]]