diff --git a/mongo.gemspec b/mongo.gemspec
index 973eebd..b9a5518 100644
--- a/mongo.gemspec
+++ b/mongo.gemspec
@@ -30,5 +30,5 @@ Gem::Specification.new do |s|
   s.email = 'mongodb-dev@googlegroups.com'
   s.homepage = 'http://www.mongodb.org'
 
-  s.add_dependency('bson', Mongo::VERSION)
+  s.add_dependency('bson', "~> #{Mongo::VERSION}")
 end