diff --git a/EdisonCore.cabal b/EdisonCore.cabal
--- a/EdisonCore.cabal
+++ b/EdisonCore.cabal
@@ -1,7 +1,7 @@
 Name:           EdisonCore
 Cabal-Version:  >= 1.10
 Build-Type:     Simple
-Version:        1.3.1
+Version:        1.3.1.1
 License:        OtherLicense
 License-File:   COPYRIGHT
 Author:         Chris Okasaki
@@ -55,7 +55,7 @@
      base == 4.*,
      mtl,
      QuickCheck >= 2.8.2 && < 3,
-     EdisonAPI,
+     EdisonAPI == 1.3.*,
      containers,
      array
   Default-Language: Haskell2010
diff --git a/src/Data/Edison/Coll/EnumSet.hs b/src/Data/Edison/Coll/EnumSet.hs
--- a/src/Data/Edison/Coll/EnumSet.hs
+++ b/src/Data/Edison/Coll/EnumSet.hs
@@ -179,7 +179,13 @@
 newtype Set a = Set Word deriving (Eq)
 
 wordLength :: Int
-wordLength = finiteBitSize (0::Word)
+wordLength =
+#if MIN_VERSION_base(4,7,0)
+  finiteBitSize
+#else
+  bitSize
+#endif
+    (0::Word)
 
 check :: String -> Int -> Int
 check msg x