diff --git a/Blaze/ByteString/Builder/Internal.hs b/Blaze/ByteString/Builder/Internal.hs
--- a/Blaze/ByteString/Builder/Internal.hs
+++ b/Blaze/ByteString/Builder/Internal.hs
@@ -63,7 +63,11 @@
 #endif
 
 import Control.Monad (unless)
+#if MIN_VERSION_base(4,4,0)
 import System.IO.Unsafe (unsafeDupablePerformIO)
+#else
+import System.IO.Unsafe (unsafePerformIO)
+#endif
 
 import qualified Data.ByteString               as S
 import qualified Data.ByteString.Internal      as S
@@ -359,11 +363,18 @@
 toByteStringIO = toByteStringIOWith defaultBufferSize
 {-# INLINE toByteStringIO #-}
 
+unsafeIO :: IO a -> a
+#if MIN_VERSION_base(4,4,0)
+unsafeIO = unsafeDupablePerformIO
+#else
+unsafeIO = unsafePerformIO
+#endif
+
 -- | Run a 'Write' to produce a strict 'S.ByteString'.
 -- This is equivalent to @('toByteString' . 'fromWrite')@, but is more
 -- efficient because it uses just one appropriately-sized buffer.
 writeToByteString :: Write -> S.ByteString
-writeToByteString !w = unsafeDupablePerformIO $ do
+writeToByteString !w = unsafeIO $ do
     fptr <- S.mallocByteString (getBound w)
     len <- withForeignPtr fptr $ \ptr -> do
         end <- runWrite w ptr
diff --git a/Blaze/ByteString/Builder/Internal/Types.hs b/Blaze/ByteString/Builder/Internal/Types.hs
--- a/Blaze/ByteString/Builder/Internal/Types.hs
+++ b/Blaze/ByteString/Builder/Internal/Types.hs
@@ -19,9 +19,7 @@
 --
 module Blaze.ByteString.Builder.Internal.Types where
 
-#ifdef APPLICATIVE_IN_BASE
 import Control.Applicative
-#endif
 
 import Data.Monoid
 import qualified Data.ByteString      as S
@@ -86,7 +84,6 @@
   fmap f (Put put) = Put $ \k -> put (\x -> k (f x))
   {-# INLINE fmap #-}
 
-#ifdef APPLICATIVE_IN_BASE
 instance Applicative Put where
   pure x = Put $ \k -> k x
   {-# INLINE pure #-}
@@ -96,7 +93,6 @@
   {-# INLINE (<*) #-}
   a *> b = Put $ \k -> unPut a (\_ -> unPut b k)
   {-# INLINE (*>) #-}
-#endif
 
 instance Monad Put where
   return x = Put $ \k -> k x
diff --git a/benchmarks/Throughput/BlazePutMonad.hs b/benchmarks/Throughput/BlazePutMonad.hs
--- a/benchmarks/Throughput/BlazePutMonad.hs
+++ b/benchmarks/Throughput/BlazePutMonad.hs
@@ -59,9 +59,7 @@
 import qualified Data.ByteString      as S
 import qualified Data.ByteString.Lazy as L
 
-#ifdef APPLICATIVE_IN_BASE
 import Control.Applicative
-#endif
 
 
 ------------------------------------------------------------------------
@@ -82,14 +80,12 @@
         fmap f m = Put $ let PairS a w = unPut m in PairS (f a) w
         {-# INLINE fmap #-}
 
-#ifdef APPLICATIVE_IN_BASE
 instance Applicative PutM where
         pure    = return
         m <*> k = Put $
             let PairS f w  = unPut m
                 PairS x w' = unPut k
             in PairS (f x) (w `mappend` w')
-#endif
 
 -- Standard Writer monad, with aggressive inlining
 instance Monad PutM where
diff --git a/blaze-builder.cabal b/blaze-builder.cabal
--- a/blaze-builder.cabal
+++ b/blaze-builder.cabal
@@ -1,5 +1,5 @@
 Name:                blaze-builder
-Version:             0.3.3.3
+Version:             0.3.3.4
 Synopsis:            Efficient buffered output.
 
 Description: