diff --git a/nmatrix.gemspec b/nmatrix.gemspec
index 19ac5ad6..31972496 100644
--- a/nmatrix.gemspec
+++ b/nmatrix.gemspec
@@ -56,7 +56,7 @@ EOF
   gem.required_ruby_version = '>= 1.9'
 
   gem.add_dependency 'packable', '~> 1.3', '>= 1.3.5'
-  gem.add_development_dependency 'bundler', '~>1.6'
+  gem.add_development_dependency 'bundler', '>=1.6'
   gem.add_development_dependency 'pry', '~>0.10'
   gem.add_development_dependency 'rake', '~>10.3'
   gem.add_development_dependency 'rake-compiler', '~>0.8'