diff --git a/.tool-versions b/.tool-versions
index 0129093..27a8619 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1 +1 @@
-ruby 2.6.9
+ruby 3.4.5
diff --git a/imessage.gemspec b/imessage.gemspec
index 8bfc2e5..bad914f 100644
--- a/imessage.gemspec
+++ b/imessage.gemspec
@@ -18,6 +18,7 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ['lib']
 
+  spec.add_dependency 'ostruct'
   spec.add_development_dependency 'rake', '~> 13.0'
   spec.add_development_dependency 'rspec', '~> 3.3'
 end
diff --git a/lib/imessage/parser.rb b/lib/imessage/parser.rb
index 220982c..09b682a 100644
--- a/lib/imessage/parser.rb
+++ b/lib/imessage/parser.rb
@@ -29,7 +29,7 @@ def opt_parser(args)
           end
 
           opts.on("-a", "--attachment [ATTACHMENT]", String, "Add an attachment") do |attachment|
-            if File.exists?(attachment)
+            if File.exist?(attachment)
               args.attachment = File.expand_path(attachment)
             else
               puts "Can not find file #{attachment}"