diff --git a/spec/integration/helper.rb b/spec/integration/helper.rb
index 400630e..07b941c 100644
--- a/spec/integration/helper.rb
+++ b/spec/integration/helper.rb
@@ -9,7 +9,7 @@ module Integration
     module_function
 
     def sysex_ok?
-      ENV['_system_name'] != 'OSX' || !RUBY_PLATFORM.include?('java')
+      !RUBY_PLATFORM.include?('java') || RbConfig::CONFIG["host_os"] != 'darwin'
     end
 
     def devices
diff --git a/spec/integration/input_spec.rb b/spec/integration/input_spec.rb
index 3073b2e..e7701df 100644
--- a/spec/integration/input_spec.rb
+++ b/spec/integration/input_spec.rb
@@ -8,7 +8,7 @@
     let(:output) { SpecHelper::Integration.devices[:output].open }
     let(:messages) { SpecHelper::Integration.numeric_messages }
     before do
-      sleep 0.1
+      sleep 0.3
       input.buffer.clear
     end
 
@@ -24,7 +24,7 @@
         p "sending: #{message}"
         output.puts(message)
         sent_bytes += message
-        sleep 0.1
+        sleep 0.3
         buffer = input.buffer.map { |m| m[:data] }.flatten
         p "received: #{buffer}"
         expect(buffer).to eq(sent_bytes)
diff --git a/spec/integration/io_spec.rb b/spec/integration/io_spec.rb
index 8a62e5c..95ff435 100644
--- a/spec/integration/io_spec.rb
+++ b/spec/integration/io_spec.rb
@@ -6,7 +6,10 @@
   # these tests assume that TestOutput is connected to TestInput
   let(:input) { SpecHelper::Integration.devices[:input].open }
   let(:output) { SpecHelper::Integration.devices[:output].open }
-
+  before do
+    sleep 0.3
+    input.buffer.clear
+  end
   after do
     input.close
     output.close
@@ -23,7 +26,7 @@
           p "sending: #{message}"
 
           output.puts(message)
-          sleep(0.1)
+          sleep 0.3
           received = input.gets.map { |m| m[:data] }.flatten
 
           p "received: #{received}"
@@ -46,7 +49,7 @@
           p "sending: #{message}"
 
           output.puts(message)
-          sleep(0.1)
+          sleep 0.3
           received = input.gets_bytestr.map { |m| m[:data] }.flatten.join
           p "received: #{received}"
 
@@ -69,7 +72,7 @@
           p "sending: #{message.inspect}"
 
           output.puts(message)
-          sleep(0.1)
+          sleep 0.3
           received = input.gets.map { |m| m[:data] }.flatten
 
           p "received: #{received}"