diff --git a/Stackage/Config.hs b/Stackage/Config.hs
index fbd0854b..9c5bd77c 100644
--- a/Stackage/Config.hs
+++ b/Stackage/Config.hs
@@ -140,10 +140,8 @@ defaultStablePackages = unPackageMap $ execWriter $ do
     mapM_ (add "Felipe Lessa <felipe.lessa@gmail.com>") $ words
         "esqueleto fb fb-persistent yesod-fb yesod-auth-fb"
 
-    -- Requires containers 0.5
-    -- https://github.com/fpco/stackage/issues/58
-    -- mapM_ (add "Alexander Altman <alexanderaltman@me.com>") $ words
-    --    "base-unicode-symbols containers-unicode-symbols"
+    mapM_ (add "Alexander Altman <alexanderaltman@me.com>") $ words
+        "base-unicode-symbols containers-unicode-symbols"
 
     -- https://github.com/fpco/stackage/issues/46
     addRange "Michael Snoyman" "QuickCheck" "< 2.6"
diff --git a/Stackage/InstallInfo.hs b/Stackage/InstallInfo.hs
index 4b0f0f6a..11776fb4 100644
--- a/Stackage/InstallInfo.hs
+++ b/Stackage/InstallInfo.hs
@@ -46,7 +46,7 @@ getInstallInfo settings = do
     let totalCore = extraCore settings `Set.union` Set.map (\(PackageIdentifier p _) -> p) core
 
     putStrLn "Loading package database"
-    pdb <- loadPackageDB settings totalCore allPackages
+    pdb <- loadPackageDB settings coreMap totalCore allPackages
 
     putStrLn "Narrowing package database"
     final <- narrowPackageDB settings totalCore pdb $ Set.fromList $ Map.toList $ Map.map snd $ allPackages
diff --git a/Stackage/LoadDatabase.hs b/Stackage/LoadDatabase.hs
index a91b55b1..09b3eac9 100644
--- a/Stackage/LoadDatabase.hs
+++ b/Stackage/LoadDatabase.hs
@@ -54,10 +54,11 @@ import           Stackage.Util
 --
 -- * For other packages, select the maximum version number.
 loadPackageDB :: SelectSettings
-              -> Set PackageName -- ^ core packages
+              -> Map PackageName Version -- ^ core packages from HP file
+              -> Set PackageName -- ^ all core packages, including extras
               -> Map PackageName (VersionRange, Maintainer) -- ^ additional deps
               -> IO PackageDB
-loadPackageDB settings core deps = do
+loadPackageDB settings coreMap core deps = do
     tarName <- getTarballName
     lbs <- L.readFile tarName
     addEntries mempty $ Tar.read lbs
@@ -139,7 +140,7 @@ loadPackageDB settings core deps = do
             checkCond' (CAnd c1 c2) = checkCond' c1 && checkCond' c2
 
             flags' = map flagName (filter flagDefault $ genPackageFlags gpd) ++
-                     (map FlagName $ Set.toList $ Stackage.Types.flags settings)
+                     (map FlagName $ Set.toList $ Stackage.Types.flags settings coreMap)
 
 -- | Attempt to grab the Github username from a homepage.
 parseGithubUserHP :: String -> Maybe String
diff --git a/Stackage/Select.hs b/Stackage/Select.hs
index ddad8496..a258eda1 100644
--- a/Stackage/Select.hs
+++ b/Stackage/Select.hs
@@ -8,6 +8,8 @@ import qualified Data.Map             as Map
 import           Data.Maybe           (mapMaybe)
 import           Data.Set             (empty)
 import qualified Data.Set             as Set
+import           Distribution.Text    (simpleParse)
+import           Distribution.Version (withinRange)
 import           Prelude              hiding (pi)
 import           Stackage.Config
 import           Stackage.InstallInfo
@@ -22,7 +24,13 @@ defaultSelectSettings = SelectSettings
     , haskellPlatformCabal = "haskell-platform/haskell-platform.cabal"
     , requireHaskellPlatform = True
     , excludedPackages = empty
-    , flags = Set.fromList $ words "blaze_html_0_5"
+    , flags = \coreMap ->
+        Set.fromList (words "blaze_html_0_5") `Set.union`
+        -- Support for containers-unicode-symbols
+        (case Map.lookup (PackageName "containers") coreMap of
+            Just v | Just range <- simpleParse "< 0.5", v `withinRange` range
+                -> Set.singleton "containers-old"
+            _ -> Set.empty)
     , disabledFlags = Set.fromList $ words "bytestring-in-base"
     , allowedPackage = const $ Right ()
     , useGlobalDatabase = False
diff --git a/Stackage/Types.hs b/Stackage/Types.hs
index 8ef0f949..2f859295 100644
--- a/Stackage/Types.hs
+++ b/Stackage/Types.hs
@@ -91,8 +91,9 @@ newtype Maintainer = Maintainer { unMaintainer :: String }
 
 data SelectSettings = SelectSettings
     { haskellPlatformCabal   :: FilePath
-    , flags                  :: Set String
-    -- ^ Compile flags which should be turned on.
+    , flags                  :: Map PackageName Version -> Set String
+    -- ^ Compile flags which should be turned on. Takes a Map providing the
+    -- core packages so that flags can be set appropriately.
     , disabledFlags          :: Set String
     -- ^ Compile flags which should always be disabled.
     , extraCore              :: Set PackageName