diff --git a/Stackage/BuildPlan.hs b/Stackage/BuildPlan.hs
index 06a77ea1..d6463a0f 100644
--- a/Stackage/BuildPlan.hs
+++ b/Stackage/BuildPlan.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE RecordWildCards   #-}
+{-# LANGUAGE TypeSynonymInstances #-}
 module Stackage.BuildPlan
     ( readBuildPlan
     , writeBuildPlan
diff --git a/Stackage/InstallInfo.hs b/Stackage/InstallInfo.hs
index b5a5c432..669ef110 100644
--- a/Stackage/InstallInfo.hs
+++ b/Stackage/InstallInfo.hs
@@ -5,6 +5,7 @@ module Stackage.InstallInfo
     ) where
 
 import           Control.Monad            (forM_, unless)
+import           Data.List                (foldl')
 import qualified Data.Map                 as Map
 import qualified Data.Set                 as Set
 import           Data.Version             (showVersion)
@@ -23,7 +24,7 @@ dropExcluded :: SelectSettings
              -> Map PackageName (VersionRange, Maintainer)
              -> Map PackageName (VersionRange, Maintainer)
 dropExcluded bs m0 =
-    Set.foldl' (flip Map.delete) m0 (excludedPackages bs)
+    foldl' (flip Map.delete) m0 (Set.toList $ excludedPackages bs)
 
 getInstallInfo :: SelectSettings -> IO InstallInfo
 getInstallInfo settings = do
diff --git a/Stackage/NarrowDatabase.hs b/Stackage/NarrowDatabase.hs
index 40309baa..42b47101 100644
--- a/Stackage/NarrowDatabase.hs
+++ b/Stackage/NarrowDatabase.hs
@@ -1,6 +1,7 @@
 module Stackage.NarrowDatabase where
 
 import           Control.Monad.Trans.Writer
+import           Data.List                  (foldl')
 import qualified Data.Map                   as Map
 import qualified Data.Set                   as Set
 import           Prelude                    hiding (pi)
@@ -46,7 +47,7 @@ narrowPackageDB settings core (PackageDB pdb) packageSet =
                                         , msg
                                         ]
                                     Right () -> return ()
-                        loop result' $ Set.foldl' (addDep users' result' maintainer) toProcess' $ Map.keysSet $ piDeps pi
+                        loop result' $ foldl' (addDep users' result' maintainer) toProcess' $ Map.keys $ piDeps pi
     addDep users result maintainer toProcess p =
         case Map.lookup p result of
             Nothing -> Set.insert (users, p, maintainer) toProcess
diff --git a/stackage.cabal b/stackage.cabal
index 42d8d517..ff8f44bf 100644
--- a/stackage.cabal
+++ b/stackage.cabal
@@ -30,7 +30,7 @@ library
                        Stackage.GhcPkg
   build-depends:       base >= 4 && < 5
                      , containers
-                     , Cabal
+                     , Cabal >= 1.14
                      , tar >= 0.3
                      , zlib
                      , bytestring