diff --git a/devise-doorkeeper.gemspec b/devise-doorkeeper.gemspec
index f11bbdb..1c1a037 100644
--- a/devise-doorkeeper.gemspec
+++ b/devise-doorkeeper.gemspec
@@ -18,7 +18,7 @@ Gem::Specification.new do |spec|
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ['lib']
 
-  spec.add_dependency 'rails'
+  spec.add_dependency 'rails', '6.1.3.2'
   spec.add_dependency 'devise'
   spec.add_dependency 'doorkeeper'