diff --git a/hiera-eyaml.gemspec b/hiera-eyaml.gemspec
index 87a6bd4..7a35ef3 100644
--- a/hiera-eyaml.gemspec
+++ b/hiera-eyaml.gemspec
@@ -16,7 +16,7 @@ Gem::Specification.new do |gem|
   gem.executables   = gem.files.grep(%r{^bin/}).map { |f| File.basename(f) }
   gem.require_paths = ['lib']
 
-  gem.add_runtime_dependency 'highline', '~> 2.1'
+  gem.add_runtime_dependency 'highline', '>= 2.1', '< 4'
   gem.add_runtime_dependency 'optimist', '~> 3.1'
 
   gem.add_development_dependency 'rake', '~> 13.2', '>= 13.2.1'