diff --git a/Pipe.cabal b/Pipe.cabal
--- a/Pipe.cabal
+++ b/Pipe.cabal
@@ -1,7 +1,7 @@
 Cabal-Version: >= 1.2
 
 Name:        Pipe
-Version:     2.1.0
+Version:     2.1.1
 Homepage:    http://iki.fi/matti.niemenmaa/pipe/
 Synopsis:    Process piping library
 Category:    System
@@ -16,7 +16,7 @@
 Build-Type: Simple
 
 Library
-   Build-Depends: base     >= 3     && < 5,
+   Build-Depends: base     >= 4     && < 5,
                   process  >= 1.0.1 && < 2,
                   filepath >= 1.1   && < 2
    Exposed-Modules: System.Process.Pipe