diff --git a/jekyll-responsive_image.gemspec b/jekyll-responsive_image.gemspec
index 1dfc8a7..848efd3 100644
--- a/jekyll-responsive_image.gemspec
+++ b/jekyll-responsive_image.gemspec
@@ -29,5 +29,5 @@ Gem::Specification.new do |spec|
   end
 
   spec.add_runtime_dependency 'jekyll', ['>= 2.0', "< #{max_jekyll_version}"]
-  spec.add_runtime_dependency 'rmagick'
+  spec.add_runtime_dependency 'rmagick', ['>= 2.0', '< 3.0']
 end