diff --git a/pure-zlib.cabal b/pure-zlib.cabal
--- a/pure-zlib.cabal
+++ b/pure-zlib.cabal
@@ -1,5 +1,5 @@
 name:                pure-zlib
-version:             0.6.3
+version:             0.6.4
 synopsis:            A Haskell-only implementation of zlib / DEFLATE
 homepage:            http://github.com/GaloisInc/pure-zlib
 license:             BSD3
@@ -22,7 +22,7 @@
   build-depends:
                       array              >= 0.4   && < 0.9,
                       base               >= 4.6   && < 5.0,
-                      base-compat        >= 0.9.1 && < 0.10,
+                      base-compat        >= 0.9.1 && < 0.11,
                       bytestring         >= 0.10  && < 0.11,
                       bytestring-builder >= 0.10  && < 0.11,
                       containers         >= 0.5   && < 0.7,
diff --git a/src/Codec/Compression/Zlib.hs b/src/Codec/Compression/Zlib.hs
--- a/src/Codec/Compression/Zlib.hs
+++ b/src/Codec/Compression/Zlib.hs
@@ -15,7 +15,7 @@
 import           Data.Bits((.|.), (.&.), shiftL, shiftR, testBit)
 import           Data.ByteString.Builder(lazyByteString,toLazyByteString)
 import qualified Data.ByteString.Lazy as L
-import           Data.Monoid((<>))
+import           Data.Semigroup ((<>))
 import           Data.Word(Word16)
 import           Prelude()
 import           Prelude.Compat