diff --git a/mollie-api-ruby.gemspec b/mollie-api-ruby.gemspec
index 6189572..9f13bfa 100644
--- a/mollie-api-ruby.gemspec
+++ b/mollie-api-ruby.gemspec
@@ -26,7 +26,7 @@ Gem::Specification.new do |s|
   s.test_files = Dir['test/**/*']
 
   s.add_dependency('ostruct', '~> 0.6.0')
-  s.add_dependency('bigdecimal', '~> 3.1', '>= 3.1.8')
+  s.add_dependency('bigdecimal', '>= 3.1.8', '< 5.0')
 
   s.add_development_dependency('rake')
   s.add_development_dependency('rubocop', '~> 0.57.2')