diff --git a/pcre-utils.cabal b/pcre-utils.cabal
--- a/pcre-utils.cabal
+++ b/pcre-utils.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                pcre-utils
-version:             0.1.8
+version:             0.1.8.1
 synopsis:            Perl-like substitute and split for PCRE regexps.
 description:         This package introduces split and replace like functions using PCRE regexps.
 license:             BSD3
@@ -28,7 +28,7 @@
   ghc-options:         -Wall
   -- ghc-prof-options:    -caf-all -auto-all
   extensions:          OverloadedStrings, BangPatterns
-  build-depends:       base >= 4.6 && < 4.10, regex-pcre-builtin >= 0.94.4.8, bytestring, attoparsec, mtl, vector, array
+  build-depends:       base >= 4.6 && < 4.10, regex-pcre-builtin >= 0.94.4.8, bytestring, attoparsec, mtl >= 2.2.1, vector, array
 
 Test-Suite test-split
     hs-source-dirs: test