diff --git a/Database/ContentIdentifier.hs b/Database/ContentIdentifier.hs
index da7f9545de..a65b4bc569 100644
--- a/Database/ContentIdentifier.hs
+++ b/Database/ContentIdentifier.hs
@@ -52,7 +52,9 @@ import qualified Utility.RawFilePath as R
 
 import Database.Persist.Sql hiding (Key)
 import Database.Persist.TH
+import Database.Persist.Sqlite (runSqlite)
 import qualified System.FilePath.ByteString as P
+import qualified Data.Text as T
 
 data ContentIdentifierHandle = ContentIdentifierHandle H.DbQueue
 
@@ -62,7 +64,6 @@ ContentIdentifiers
   cid ContentIdentifier
   key Key
   ContentIndentifiersKeyRemoteCidIndex key remote cid
-  ContentIndentifiersCidRemoteIndex cid remote
 -- The last git-annex branch tree sha that was used to update
 -- ContentIdentifiers
 AnnexBranch
@@ -79,9 +80,15 @@ openDb :: Annex ContentIdentifierHandle
 openDb = do
 	dbdir <- fromRepo gitAnnexContentIdentifierDbDir
 	let db = dbdir P.</> "db"
-	unlessM (liftIO $ R.doesPathExist db) $ do
-		initDb db $ void $
+	ifM (liftIO $ not <$> R.doesPathExist db)
+		( initDb db $ void $ 
 			runMigrationSilent migrateContentIdentifier
+		-- Migrate from old version of database, which had
+		-- an incorrect uniqueness constraint on the
+		-- ContentIdentifiers table.
+		, liftIO $ runSqlite (T.pack (fromRawFilePath db)) $ void $
+			runMigrationSilent migrateContentIdentifier
+		)
 	h <- liftIO $ H.openDbQueue H.SingleWriter db "content_identifiers"
 	return $ ContentIdentifierHandle h
 
diff --git a/doc/bugs/borg_uses_non_unique_contentidentifier_which_gets_lost.mdwn b/doc/bugs/borg_uses_non_unique_contentidentifier_which_gets_lost.mdwn
index 1138c908a5..a5a4febacd 100644
--- a/doc/bugs/borg_uses_non_unique_contentidentifier_which_gets_lost.mdwn
+++ b/doc/bugs/borg_uses_non_unique_contentidentifier_which_gets_lost.mdwn
@@ -1,6 +1,6 @@
 borg uses a non-unique ContentIdentifier ("") for everything.
-I think this is why, it eventually gets lost from the sqlite database,
-preventing retrieval of content from the remote.
+I think this is why, it eventually gets lost from the sqlite database for
+some keys, preventing retrieval of content from the remote.
 
 Repositories affected by this problem can be fixed up by just:
 `rm -rf .git/annex/cidsdb`
@@ -24,4 +24,5 @@ And if a remote uses a hash for generating ContentIdentifiers, two different
 Key can have the same content in edge cases.
 
 So, need to upgrade the database, removing this constraint from it.
---[[Joey]]
+
+>> [[done]] --[[Joey]]