diff --git a/devicecheck.gemspec b/devicecheck.gemspec
index 03b68d9..c87838d 100644
--- a/devicecheck.gemspec
+++ b/devicecheck.gemspec
@@ -32,7 +32,7 @@ Gem::Specification.new do |spec|
   spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
   spec.require_paths = ['lib']
 
-  spec.add_dependency 'base64', '~> 0.2.0'
+  spec.add_dependency 'base64', '>= 0.2', '< 0.4'
   spec.add_dependency 'cbor', '~> 0.5.9'
   spec.add_dependency 'openssl', '~> 3'