diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,7 @@
+0.1.2.1
+-----
+* Add explicit quantification to type synonyms for building on GHC 8
+
 0.1.2
 -----
 * `profunctors` 5 support.
diff --git a/src/Codec/Compression/Zlib/Lens.hs b/src/Codec/Compression/Zlib/Lens.hs
--- a/src/Codec/Compression/Zlib/Lens.hs
+++ b/src/Codec/Compression/Zlib/Lens.hs
@@ -64,8 +64,8 @@
 import qualified Data.ByteString.Lazy as L (ByteString)
 import Data.Profunctor (Profunctor(dimap))
 
-type Lens' s a = Functor f => (a -> f a) -> s -> f s
-type Iso' s a = (Functor f, Profunctor p) => p a (f a) -> p s (f s)
+type Lens' s a = forall p f. Functor f => (a -> f a) -> s -> f s
+type Iso' s a = forall p f. (Functor f, Profunctor p) => p a (f a) -> p s (f s)
 
 -- |
 -- The 'zlib' compression format.
diff --git a/zlib-lens.cabal b/zlib-lens.cabal
--- a/zlib-lens.cabal
+++ b/zlib-lens.cabal
@@ -1,5 +1,5 @@
 name:                zlib-lens
-version:             0.1.2
+version:             0.1.2.1
 synopsis:            Lenses for zlib
 description:         Lenses for zlib
 homepage:            http://lens.github.io/
@@ -23,7 +23,7 @@
   other-extensions:    Rank2Types
   build-depends:       base        >= 4.0      && < 5,
                        bytestring  >= 0.9.1.10 && < 0.11,
-                       zlib        >= 0.5.4    && < 0.6,
+                       zlib        >= 0.5.4    && < 0.7,
                        profunctors >= 3.1.1    && < 6
 
   hs-source-dirs:      src