diff --git a/.travis.yml b/.travis.yml
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,11 +6,16 @@
   - travis/cabal-apt-install $mode
 
 install:
+  - export PATH=~/.cabal/bin:$PATH
   - cabal configure -flib-Werror $mode
+  - cabal install packdeps packunused
   - cabal build
 
 script:
-  - $script && hlint src --cpp-define HLINT
+  - $script
+  - packdeps bytes.cabal
+  - packunused --ignore-package=transformers-compat
+  - hlint src --cpp-define HLINT
 
 notifications:
   irc:
diff --git a/bytes.cabal b/bytes.cabal
--- a/bytes.cabal
+++ b/bytes.cabal
@@ -1,6 +1,6 @@
 name:          bytes
 category:      Data, Serialization
-version:       0.14
+version:       0.14.0.1
 license:       BSD3
 cabal-version: >= 1.8
 license-file:  LICENSE
@@ -49,13 +49,15 @@
     bytestring                >= 0.9      && < 0.11,
     cereal                    >= 0.3.5    && < 0.5,
     containers                >= 0.3      && < 1,
-    ghc-prim,
-    mtl                       >= 2.0      && < 2.2,
+    mtl                       >= 2.0      && < 2.3,
     text                      >= 0.2      && < 1.2,
     time                      >= 1.2      && < 1.5,
-    transformers              >= 0.2      && < 0.4,
+    transformers              >= 0.2      && < 0.5,
     transformers-compat       >= 0.1      && < 1,
     void                      >= 0.6      && < 0.7
+
+  if impl(ghc >= 7.4 && < 7.6)
+    build-depends: ghc-prim
 
   exposed-modules:
     Data.Bytes.Get