diff --git a/pem.cabal b/pem.cabal
--- a/pem.cabal
+++ b/pem.cabal
@@ -1,5 +1,5 @@
 Name:                pem
-Version:             0.2.0
+Version:             0.2.1
 Description:         Privacy Enhanced Mail (PEM) format reader and writer.
 License:             BSD3
 License-file:        LICENSE
@@ -19,7 +19,7 @@
   Build-Depends:     base >= 3 && < 5
                    , mtl
                    , bytestring
-                   , base64-bytestring
+                   , base64-bytestring >= 1.0.0
   Exposed-modules:   Data.PEM
   Other-modules:     Data.PEM.Parser
                      Data.PEM.Writer