diff --git a/test/helper.rb b/test/helper.rb
index 887964a6..d230c60b 100644
--- a/test/helper.rb
+++ b/test/helper.rb
@@ -43,6 +43,15 @@ def hit(uris)
   end
 end
 
+module UniquePort
+  @port  = 3211
+
+  def self.call
+    @port += 1
+    @port
+  end
+end
+
 module TimeoutEveryTestCase
   # our own subclass so we never confused different timeouts
   class TestTookTooLong < Timeout::Error
diff --git a/test/test_persistent.rb b/test/test_persistent.rb
index 94d7cc19..06ec90aa 100644
--- a/test/test_persistent.rb
+++ b/test/test_persistent.rb
@@ -21,14 +21,14 @@ class TestPersistent < Minitest::Test
     end
 
     @host = "127.0.0.1"
-    @port = 9988
+    @port = UniquePort.call
 
     @server = Puma::Server.new @simple
-    @server.add_tcp_listener "127.0.0.1", 9988
+    @server.add_tcp_listener "127.0.0.1", @port
     @server.max_threads = 1
     @server.run
 
-    @client = TCPSocket.new "127.0.0.1", 9988
+    @client = TCPSocket.new "127.0.0.1", @port
   end
 
   def teardown
diff --git a/test/test_puma_server_ssl.rb b/test/test_puma_server_ssl.rb
index 33afc080..89040353 100644
--- a/test/test_puma_server_ssl.rb
+++ b/test/test_puma_server_ssl.rb
@@ -22,7 +22,7 @@ class TestPumaServerSSL < Minitest::Test
 
   def setup
     return if DISABLE_SSL
-    port = 3212
+    port = UniquePort.call
     host = "127.0.0.1"
 
     app = lambda { |env| [200, {}, [env['rack.url_scheme']]] }
diff --git a/test/test_tcp_rack.rb b/test/test_tcp_rack.rb
index f746c406..10ab7fe4 100644
--- a/test/test_tcp_rack.rb
+++ b/test/test_tcp_rack.rb
@@ -3,7 +3,7 @@ require_relative "helper"
 class TestTCPRack < Minitest::Test
 
   def setup
-    @port = 3212
+    @port = UniquePort.call
     @host = "127.0.0.1"
 
     @events = Puma::Events.new STDOUT, STDERR