diff --git a/.ruby-version b/.ruby-version
index 2bf1c1c..ec1cf33 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-2.3.1
+2.6.3
diff --git a/ruby3mf.gemspec b/ruby3mf.gemspec
index b7bcf05..e686f68 100644
--- a/ruby3mf.gemspec
+++ b/ruby3mf.gemspec
@@ -19,7 +19,7 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_development_dependency "bundler", "~> 1.11"
+  spec.add_development_dependency "bundler", "~> 2.1.4"
   spec.add_development_dependency "rake", "~> 10.0"
   spec.add_development_dependency "rspec", "~> 3.5"
   spec.add_development_dependency "simplecov"
@@ -27,6 +27,6 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency 'rubyzip'
   spec.add_runtime_dependency 'nokogiri', '>=1.8.1'
   spec.add_runtime_dependency 'mimemagic'
-  spec.add_runtime_dependency 'mini_magick', '~> 4.6'
+  spec.add_runtime_dependency 'mini_magick', '~> 4.10.1'
   spec.add_runtime_dependency 'addressable', '~> 2.5'
 end