diff --git a/.gitignore b/.gitignore
index 02f82a6..8d43764 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 .cabal-sandbox
 cabal.sandbox.config
 dist/
+.stack-work
diff --git a/Data/Binary/Bits/Get.hs b/Data/Binary/Bits/Get.hs
index 1f7fc47..44f8d63 100644
--- a/Data/Binary/Bits/Get.hs
+++ b/Data/Binary/Bits/Get.hs
@@ -272,7 +272,6 @@ newtype BitGet a = B { runState :: S -> Get (S,a) }
 
 instance Monad BitGet where
   return x = B $ \s -> return (s,x)
-  fail str = B $ \s -> putBackState s >> fail str
   (B f) >>= g = B $ \s -> do (s',a) <- f s
                              runState (g a) s'
 
diff --git a/Data/Binary/Bits/Internal.hs b/Data/Binary/Bits/Internal.hs
index 5869a89..39e55b8 100644
--- a/Data/Binary/Bits/Internal.hs
+++ b/Data/Binary/Bits/Internal.hs
@@ -116,13 +116,13 @@ shiftr_w32 :: Word32 -> Int -> Word32
 shiftr_w64 :: Word64 -> Int -> Word64
 
 #if defined(__GLASGOW_HASKELL__) && !defined(__HADDOCK__)
-shiftl_w8  (W8# w)  (I# i) = W8#  (w `uncheckedShiftL#`   i)
-shiftl_w16 (W16# w) (I# i) = W16# (w `uncheckedShiftL#`   i)
-shiftl_w32 (W32# w) (I# i) = W32# (w `uncheckedShiftL#`   i)
+shiftl_w8   w  i = w `unsafeShiftL`   i
+shiftl_w16 w i = w `unsafeShiftL`   i
+shiftl_w32 w i = w `unsafeShiftL`   i
 
-shiftr_w8  (W8#  w) (I# i) = W8# (w `uncheckedShiftRL#`   i)
-shiftr_w16 (W16# w) (I# i) = W16# (w `uncheckedShiftRL#`  i)
-shiftr_w32 (W32# w) (I# i) = W32# (w `uncheckedShiftRL#`  i)
+shiftr_w8   w i = w `unsafeShiftR`   i
+shiftr_w16 w i = w `unsafeShiftR`  i
+shiftr_w32 w i = w `unsafeShiftR`  i
 
 
 #if WORD_SIZE_IN_BITS < 64
diff --git a/stack.yaml b/stack.yaml
new file mode 100644
index 0000000..9d857a1
--- /dev/null
+++ b/stack.yaml
@@ -0,0 +1,67 @@
+# This file was automatically generated by 'stack init'
+#
+# Some commonly used options have been documented as comments in this file.
+# For advanced use and comprehensive documentation of the format, please see:
+# https://docs.haskellstack.org/en/stable/yaml_configuration/
+
+# Resolver to choose a 'specific' stackage snapshot or a compiler version.
+# A snapshot resolver dictates the compiler version and the set of packages
+# to be used for project dependencies. For example:
+#
+# resolver: lts-3.5
+# resolver: nightly-2015-09-21
+# resolver: ghc-7.10.2
+#
+# The location of a snapshot can be provided as a file or url. Stack assumes
+# a snapshot provided as a file might change, whereas a url resource does not.
+#
+# resolver: ./custom-snapshot.yaml
+# resolver: https://example.com/snapshots/2018-01-01.yaml
+resolver:
+  url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/21/6.yaml
+
+# User packages to be built.
+# Various formats can be used as shown in the example below.
+#
+# packages:
+# - some-directory
+# - https://example.com/foo/bar/baz-0.0.2.tar.gz
+#   subdirs:
+#   - auto-update
+#   - wai
+packages:
+- .
+# Dependency packages to be pulled from upstream that are not in the resolver.
+# These entries can reference officially published versions as well as
+# forks / in-progress versions pinned to a git hash. For example:
+#
+# extra-deps:
+# - acme-missiles-0.3
+# - git: https://github.com/commercialhaskell/stack.git
+#   commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+#
+# extra-deps: []
+
+# Override default flag values for local packages and extra-deps
+# flags: {}
+
+# Extra package databases containing global packages
+# extra-package-dbs: []
+
+# Control whether we use the GHC we find on the path
+# system-ghc: true
+#
+# Require a specific version of stack, using version ranges
+# require-stack-version: -any # Default
+# require-stack-version: ">=2.9"
+#
+# Override the architecture used by stack, especially useful on Windows
+# arch: i386
+# arch: x86_64
+#
+# Extra directories used by stack for building
+# extra-include-dirs: [/path/to/dir]
+# extra-lib-dirs: [/path/to/dir]
+#
+# Allow a newer minor version of GHC than the snapshot specifies
+# compiler-check: newer-minor
diff --git a/stack.yaml.lock b/stack.yaml.lock
new file mode 100644
index 0000000..59b8474
--- /dev/null
+++ b/stack.yaml.lock
@@ -0,0 +1,13 @@
+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages: []
+snapshots:
+- completed:
+    sha256: 2e7d4a730d8eb5373b2d383fac84efcf7c81e3b7a5fce71b4c2e19a1768f25a6
+    size: 640239
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/21/6.yaml
+  original:
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/21/6.yaml