diff --git a/Data/IntMap/Lazy/Unicode.hs b/Data/IntMap/Lazy/Unicode.hs
--- a/Data/IntMap/Lazy/Unicode.hs
+++ b/Data/IntMap/Lazy/Unicode.hs
@@ -1,4 +1,6 @@
-{-# LANGUAGE NoImplicitPrelude, UnicodeSyntax #-}
+{-# LANGUAGE CPP               #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE UnicodeSyntax     #-}
 
 {-|
 Module     : Data.IntMap.Lazy.Unicode
@@ -24,11 +26,17 @@
 import Data.Function ( flip )
 
 -- from containers:
-import Data.IntMap.Lazy ( IntMap
-                        , member, notMember
-                        , empty
-                        , union, difference, intersection
-                        )
+#ifdef CONTAINERS_OLD
+#define MODULE Data.IntMap
+#else
+#define MODULE Data.IntMap.Lazy
+#endif
+import MODULE ( IntMap
+              , member, notMember
+              , empty
+              , union, difference, intersection
+              )
+#undef MODULE
 
 
 -------------------------------------------------------------------------------
diff --git a/Data/Map/Lazy/Unicode.hs b/Data/Map/Lazy/Unicode.hs
--- a/Data/Map/Lazy/Unicode.hs
+++ b/Data/Map/Lazy/Unicode.hs
@@ -1,4 +1,6 @@
-{-# LANGUAGE NoImplicitPrelude, UnicodeSyntax #-}
+{-# LANGUAGE CPP               #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE UnicodeSyntax     #-}
 
 {-|
 Module     : Data.Map.Lazy.Unicode
@@ -24,12 +26,17 @@
 import Data.Function ( flip )
 
 -- from containers:
-import Data.Map.Lazy ( Map
-                     , member, notMember
-                     , empty
-                     , union, difference, intersection
-                     )
-
+#ifdef CONTAINERS_OLD
+#define MODULE Data.Map
+#else
+#define MODULE Data.Map.Lazy
+#endif
+import MODULE ( Map
+              , member, notMember
+              , empty
+              , union, difference, intersection
+              )
+#undef MODULE
 
 -------------------------------------------------------------------------------
 -- Fixities
diff --git a/Data/Map/Unicode.hs b/Data/Map/Unicode.hs
--- a/Data/Map/Unicode.hs
+++ b/Data/Map/Unicode.hs
@@ -8,7 +8,7 @@
 -}
 
 module Data.Map.Unicode
-    ( module Data.Map.Strict.Unicode
+    ( module Data.Map.Lazy.Unicode
     ) where
 
-import Data.Map.Strict.Unicode
+import Data.Map.Lazy.Unicode
diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright 2009–2012 Roel van Dijk
+Copyright 2009–2013 Roel van Dijk
 
 All rights reserved.
 
diff --git a/containers-unicode-symbols.cabal b/containers-unicode-symbols.cabal
--- a/containers-unicode-symbols.cabal
+++ b/containers-unicode-symbols.cabal
@@ -1,11 +1,11 @@
 name:          containers-unicode-symbols
-version:       0.3.1
+version:       0.3.1.1
 cabal-version: >=1.6
 build-type:    Simple
 stability:     provisional
 author:        Roel van Dijk <vandijk.roel@gmail.com>
 maintainer:    Roel van Dijk <vandijk.roel@gmail.com>
-copyright:     2009—2012 Roel van Dijk <vandijk.roel@gmail.com>
+copyright:     2009—2013 Roel van Dijk <vandijk.roel@gmail.com>
 license:       BSD3
 license-file:  LICENSE
 category:
@@ -26,18 +26,27 @@
   type:     git
   location: git://github.com/roelvandijk/containers-unicode-symbols.git
 
+flag containers-old
+  description: Support containers < 0.5
+  default: False
+
 library
   exposed-modules: Data.IntMap.Unicode
-                 , Data.IntMap.Lazy.Unicode
-                 , Data.IntMap.Strict.Unicode
                  , Data.IntSet.Unicode
                  , Data.Map.Unicode
-                 , Data.Map.Lazy.Unicode
-                 , Data.Map.Strict.Unicode
                  , Data.Sequence.Unicode
                  , Data.Set.Unicode
   build-depends: base                 >= 3.0.3.1 && < 5
                , base-unicode-symbols >= 0.1.1   && < 0.3
-               , containers           >= 0.5     && < 0.6
+
+  if flag(containers-old)
+    build-depends: containers >= 0.4 && < 0.5
+    cpp-options: -DCONTAINERS_OLD
+  else
+    build-depends: containers >= 0.5 && < 0.6
+    exposed-modules: Data.IntMap.Lazy.Unicode
+                   , Data.IntMap.Strict.Unicode
+                   , Data.Map.Lazy.Unicode
+                   , Data.Map.Strict.Unicode
 
   ghc-options: -Wall