diff --git a/active_record_union.gemspec b/active_record_union.gemspec
index 0c9a6b3..95cdd34 100644
--- a/active_record_union.gemspec
+++ b/active_record_union.gemspec
@@ -20,7 +20,7 @@ Gem::Specification.new do |spec|
 
   spec.add_dependency "activerecord", ">= 4.0"
 
-  spec.add_development_dependency "bundler", "~> 1.6"
+  spec.add_development_dependency "bundler"
   spec.add_development_dependency "rake"
   spec.add_development_dependency "rspec",   "~> 3.0"
   spec.add_development_dependency "pry"