diff --git a/composer.json b/composer.json
index 678b01a..b18335b 100644
--- a/composer.json
+++ b/composer.json
@@ -38,7 +38,8 @@
         "apigen/apigen": "^4.1",
         "mockery/mockery": "^0.9.4",
         "goaop/framework": "1.0.0-alpha.2",
-        "codeception/aspect-mock": "1.0.0"
+        "codeception/aspect-mock": "1.0.0",
+        "php-mock/php-mock-phpunit": "^0.3|^1.1"
     },
     "suggest": {
         "ircmaxell/random-lib": "Provides RandomLib for use with the RandomLibAdapter",
diff --git a/tests/Generator/SodiumRandomGeneratorTest.php b/tests/Generator/SodiumRandomGeneratorTest.php
index 9579b18..d118fd3 100644
--- a/tests/Generator/SodiumRandomGeneratorTest.php
+++ b/tests/Generator/SodiumRandomGeneratorTest.php
@@ -2,12 +2,15 @@
 
 namespace Ramsey\Uuid\Test\Generator;
 
+use phpmock\phpunit\PHPMock;
 use Ramsey\Uuid\Test\TestCase;
 use Ramsey\Uuid\Generator\SodiumRandomGenerator;
 
 class SodiumRandomGeneratorTest extends TestCase
 {
-    protected function setUp()
+    use PHPMock;
+
+    protected function skipIfLibsodiumExtensionNotLoaded()
     {
         if (!extension_loaded('libsodium')) {
             $this->markTestSkipped(
@@ -18,6 +21,7 @@ class SodiumRandomGeneratorTest extends TestCase
 
     public function testGenerateReturnsBytes()
     {
+        $this->skipIfLibsodiumExtensionNotLoaded();
         $generator = new SodiumRandomGenerator();
 
         $bytes = $generator->generate(16);
@@ -28,6 +32,7 @@ class SodiumRandomGeneratorTest extends TestCase
 
     public function testFactoryUsesSodiumRandomGenerator()
     {
+        $this->skipIfLibsodiumExtensionNotLoaded();
         $uuidFactory = new \Ramsey\Uuid\UuidFactory();
         $uuidFactory->setRandomGenerator(new SodiumRandomGenerator());
         \Ramsey\Uuid\Uuid::setFactory($uuidFactory);
@@ -39,4 +44,17 @@ class SodiumRandomGeneratorTest extends TestCase
             $uuid->getFactory()->getRandomGenerator()
         );
     }
+
+    /**
+     * @runInSeparateProcess
+     * @preserveGlobalState disabled
+     */
+    public function testGenerateUsesSodiumLibrary()
+    {
+        $randomBytesFunc = $this->getFunctionMock('Sodium', 'randombytes_buf');
+        $randomBytesFunc->expects($this->once())
+            ->with(10);
+        $generator = new SodiumRandomGenerator();
+        $generator->generate(10);
+    }
 }