diff --git a/Gemfile b/Gemfile
index fa75df1..05cbb03 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,4 @@
 source 'https://rubygems.org'
 
 gemspec
+gem 'stackprof', platforms: :mri_21
diff --git a/liquid.gemspec b/liquid.gemspec
index 1b0ae1e..0cd2f86 100644
--- a/liquid.gemspec
+++ b/liquid.gemspec
@@ -24,6 +24,5 @@ Gem::Specification.new do |s|
 
   s.require_path = "lib"
 
-  s.add_development_dependency 'stackprof' if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new("2.1.0")
   s.add_development_dependency 'rake'
 end