diff --git a/html-pipeline.gemspec b/html-pipeline.gemspec
index 9737aa6f..dd625aad 100644
--- a/html-pipeline.gemspec
+++ b/html-pipeline.gemspec
@@ -16,7 +16,7 @@ Gem::Specification.new do |gem|
   gem.require_paths = ["lib"]
 
   gem.add_dependency "nokogiri",      RUBY_VERSION < "1.9.2" ? [">= 1.4", "< 1.6"] : "~> 1.4"
-  gem.add_dependency "activesupport", RUBY_VERSION < "1.9.3" ? [">= 2", "< 4"] : ">= 2"
+  gem.add_dependency "activesupport", RUBY_VERSION < "1.9.3" ? [">= 2", "< 4"] : [">= 2", "< 4.1"]
 
   gem.post_install_message = <<msg
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