diff --git a/actionpack/actionpack.gemspec b/actionpack/actionpack.gemspec
index 02ff908c1cb729fd776b95ed6a334d8cea6f02c8..8e95315252ce9ebee6f80b79708df82af3e38aa4 100644
--- a/actionpack/actionpack.gemspec
+++ b/actionpack/actionpack.gemspec
@@ -25,7 +25,7 @@
   s.add_dependency('i18n',          '~> 0.4.1')
   s.add_dependency('rack',          '~> 1.1.0')
   s.add_dependency('rack-test',     '~> 0.5.4')
-  s.add_dependency('rack-mount',    '~> 0.6.3')
+  s.add_dependency('rack-mount',    '~> 0.6.4')
   s.add_dependency('tzinfo',        '~> 0.3.16')
   s.add_dependency('erubis',        '~> 2.6.5')
 end