diff --git a/Bio/TwoBit.hs b/Bio/TwoBit.hs
--- a/Bio/TwoBit.hs
+++ b/Bio/TwoBit.hs
@@ -455,5 +455,8 @@
     w <- fromIntegral <$> peekWord8 (plusPtr p 3)
     return $! w .|. unsafeShiftL z 8 .|. unsafeShiftL y 16 .|. unsafeShiftL x 24
 
+peekWord8 :: Ptr a -> IO Word8
+peekWord8 = peek . castPtr
+
 #endif
 
diff --git a/twobitreader.cabal b/twobitreader.cabal
--- a/twobitreader.cabal
+++ b/twobitreader.cabal
@@ -1,6 +1,6 @@
 Cabal-version:       2.0
 Name:                twobitreader
-Version:             1.0
+Version:             1.0.1
 Synopsis:            reader for the 2bit file format
 Category:            Bioinformatics
 Description:
@@ -27,7 +27,7 @@
 Library
   Exposed-modules:     Bio.TwoBit Bio.TwoBit.Tool
 
-  Build-depends:       base                     >= 4.8 && < 4.21,
+  Build-depends:       base                     >= 4.8 && < 4.22,
                        bytestring               >= 0.10.6 && < 0.13,
                        mmap                     == 0.5.*,
                        primitive                >= 0.6.1 && < 0.10,
@@ -43,7 +43,7 @@
   Hs-source-dirs:      tool
   Default-Language:    Haskell2010
 
-  Build-depends:       base                     >= 4.8 && < 4.21,
+  Build-depends:       base                     >= 4.8 && < 4.22,
                        bytestring               >= 0.10.6 && < 0.13,
                        directory                >= 1.2.2 && < 1.4,
                        optparse-applicative     >= 0.13 && < 0.19,