diff --git a/.travis.yml b/.travis.yml
index f1b4153..8fba74e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,4 @@
 language: ruby
 rvm:
-  - 2.1.8
-  - 2.2.3
-  - 2.3.1
-before_install: gem install bundler -v 1.10.6
+  - 3.3.4
+before_install: gem install bundler -v 2.5
diff --git a/lib/thread/inheritable_attributes.rb b/lib/thread/inheritable_attributes.rb
index 7b02b99..ed2a2f3 100644
--- a/lib/thread/inheritable_attributes.rb
+++ b/lib/thread/inheritable_attributes.rb
@@ -9,7 +9,7 @@ def initialize(*args, &block)
     _inheritable_attributes = inheritable_attributes.dup
     _initialize(*args) do |*block_args|
       store[:inheritable_attributes] = _inheritable_attributes
-      block.call(block_args)
+      block.call(*block_args)
     end
   end
 
diff --git a/spec/thread/inheritable_attributes_spec.rb b/spec/thread/inheritable_attributes_spec.rb
index fac4f30..8fe7bd2 100644
--- a/spec/thread/inheritable_attributes_spec.rb
+++ b/spec/thread/inheritable_attributes_spec.rb
@@ -1,4 +1,5 @@
 require "thread/inheritable_attributes"
+require "securerandom"
 
 RSpec.describe Thread do
   after { Thread.current.send(:store)[:inheritable_attributes] = nil }
@@ -33,6 +34,13 @@
       Thread.new(a, b, c) { |d, e, f| arr << d << e << f }.join
       expect(arr).to eq [1, 2, 3]
     end
+
+    it "single arg is expanded properly" do
+      total = 1
+      a = 7
+      Thread.new(a) { |b| total += b }.join
+      expect(total).to eq 8
+    end
   end
 
   describe "#get_inheritable_attribute" do
diff --git a/thread-inheritable_attributes.gemspec b/thread-inheritable_attributes.gemspec
index 304bb93..10d8f38 100644
--- a/thread-inheritable_attributes.gemspec
+++ b/thread-inheritable_attributes.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", "~> 1.10"
+  spec.add_development_dependency "bundler", "~> 2.5"
   spec.add_development_dependency "rake", "~> 10.0"
   spec.add_development_dependency "rspec", "~> 3.4"
   spec.add_runtime_dependency "request_store", "~> 1.3"