diff --git a/digest.gemspec b/digest.gemspec
index 37f1654..7a4291c 100644
--- a/digest.gemspec
+++ b/digest.gemspec
@@ -3,7 +3,7 @@
 
 Gem::Specification.new do |spec|
   spec.name          = "digest"
-  spec.version       = "3.1.0.pre1"
+  spec.version       = "3.1.0.pre2"
   spec.authors       = ["Akinori MUSHA"]
   spec.email         = ["knu@idaemons.org"]