diff --git a/.travis.yml b/.travis.yml
index 52e6eb7..a7200a8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,9 +2,10 @@ services:
   - mongodb
 language: ruby
 rvm:
-  - 2.2.5
-  - 2.3.1
-  - 2.4.1
+  - 2.4.10
+  - 2.5.8
+  - 2.6.6
+  - 2.7.1
 env:
   global:
     - RUBYOPT=-W1
diff --git a/Rakefile b/Rakefile
index db5c3fb..8db5423 100644
--- a/Rakefile
+++ b/Rakefile
@@ -7,16 +7,19 @@ namespace :test do
 
   Rake::TestTask.new(:unit) do |t|
     t.libs << 'test'
+    t.warning = false
     t.pattern = Dir.glob('test/unit/*_test.rb')
   end
 
   Rake::TestTask.new(:integration) do |t|
     t.libs << 'test'
+    t.warning = false
     t.pattern = Dir.glob('test/integration/*_test.rb')
   end
 
   Rake::TestTask.new(:performance) do |t|
     t.libs << 'test'
+    t.warning = false
     t.pattern = Dir.glob('test/performance/*_test.rb')
   end
 
diff --git a/test/unit/handler_test.rb b/test/unit/handler_test.rb
index da9d3eb..1898f97 100644
--- a/test/unit/handler_test.rb
+++ b/test/unit/handler_test.rb
@@ -21,7 +21,9 @@ def setup
 
   def test_should_instantiate_controller_and_call_corresponding_method
     status, headers, body = @handler.call env_for(:get, '/')
-    assert_equal 'GET', body.body.join
+    body_str = ''
+    body.each{|s| body_str << s}
+    assert_equal 'GET', body_str
     assert_equal '3', headers['Content-Length']
     assert_equal 200, status
   end