diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 7993f0b..017916a 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -11,8 +11,13 @@
         verbose="true"
         >
     <php>
-        <!-- To override, "export PORT=8081" -->
-        <env name="PORT" value="8080" />
+        <!-- Port for testing the Client class. Set this to a port that is not used on the system.
+             Use a range (e.g., 2000-9000) to randomly pick a port within the boundaries.
+             To override, "export PORT=8081"
+        -->
+        <env name="PORT" value="2000-9000" />
+        <!-- Port for testing Client class failuers. Set this to a port that is not used on the system. -->
+        <env name="FAIL_PORT" value="9001-9100" />
     </php>
     <testsuites>
         <testsuite name="WellRESTed Test Suite">
diff --git a/test/ClientTest.php b/test/ClientTest.php
index c3369f0..c215356 100644
--- a/test/ClientTest.php
+++ b/test/ClientTest.php
@@ -15,7 +15,7 @@ class ClientTest extends \PHPUnit_Framework_TestCase
     public function testSendHttpMethod($method)
     {
         $host = "localhost";
-        $port = getenv("PORT");
+        $port = $this->getRandomNumberInRange(getenv("PORT"));
         $script = realpath(__DIR__ . "/sham-routers/method.php");
 
         $server = new ShamServer($host, $port, $script);
@@ -60,7 +60,7 @@ class ClientTest extends \PHPUnit_Framework_TestCase
     public function testSendHttpHeaders($headerKey, $headerValue)
     {
         $host = "localhost";
-        $port = getenv("PORT");
+        $port = $this->getRandomNumberInRange(getenv("PORT"));
         $script = realpath(__DIR__ . "/sham-routers/headers.php");
 
         $server = new ShamServer($host, $port, $script);
@@ -102,7 +102,7 @@ class ClientTest extends \PHPUnit_Framework_TestCase
     public function testSendBody($body)
     {
         $host = "localhost";
-        $port = getenv("PORT");
+        $port = $this->getRandomNumberInRange(getenv("PORT"));
         $script = realpath(__DIR__ . "/sham-routers/body.php");
         $server = new ShamServer($host, $port, $script);
 
@@ -145,7 +145,7 @@ class ClientTest extends \PHPUnit_Framework_TestCase
     public function testSendForm($form)
     {
         $host = "localhost";
-        $port = getenv("PORT");
+        $port = $this->getRandomNumberInRange(getenv("PORT"));
         $script = realpath(__DIR__ . "/sham-routers/formFields.php");
         $server = new ShamServer($host, $port, $script);
 
@@ -178,7 +178,7 @@ class ClientTest extends \PHPUnit_Framework_TestCase
     public function testSetCustomCurlOptionsOnInstantiation()
     {
         $host = "localhost";
-        $port = getenv("PORT");
+        $port = $this->getRandomNumberInRange(getenv("PORT"));
         $script = realpath(__DIR__ . "/sham-routers/headers.php");
         $server = new ShamServer($host, $port, $script);
 
@@ -208,7 +208,7 @@ class ClientTest extends \PHPUnit_Framework_TestCase
     public function testSetCustomCurlOptionsOnRequest()
     {
         $host = "localhost";
-        $port = getenv("PORT");
+        $port = $this->getRandomNumberInRange(getenv("PORT"));
         $script = realpath(__DIR__ . "/sham-routers/headers.php");
         $server = new ShamServer($host, $port, $script);
 
@@ -261,12 +261,24 @@ class ClientTest extends \PHPUnit_Framework_TestCase
 
     public function curlErrorProvider()
     {
+        $port = $this->getRandomNumberInRange(getenv("FAIL_PORT"));
         return [
-            ["http://localhost:9991", [
+            ["http://localhost:{$port}", [
                 CURLOPT_FAILONERROR, true,
                 CURLOPT_TIMEOUT_MS, 10
             ]],
         ];
     }
 
+    private function getRandomNumberInRange($range)
+    {
+        static $pattern = '/(\d+)\-(\d+)/';
+        if (preg_match($pattern, $range, $matches)) {
+            $lower = $matches[1];
+            $upper = $matches[2];
+            return rand($lower, $upper);
+        } else {
+            return $range;
+        }
+    }
 }