diff --git a/src/Symfony/Component/Process/ProcessBuilder.php b/src/Symfony/Component/Process/ProcessBuilder.php
index ae811e0843..2a5e1db831 100644
--- a/src/Symfony/Component/Process/ProcessBuilder.php
+++ b/src/Symfony/Component/Process/ProcessBuilder.php
@@ -164,7 +164,8 @@ class ProcessBuilder
         $script = implode(' ', array_map(array(__NAMESPACE__.'\\ProcessUtils', 'escapeArgument'), $arguments));
 
         if ($this->inheritEnv) {
-            $env = $this->env ? $this->env + $_ENV : null;
+            // include $_ENV for BC purposes 
+            $env = array_replace($_ENV, $_SERVER, $this->env); 
         } else {
             $env = $this->env;
         }
diff --git a/src/Symfony/Component/Process/Tests/ProcessBuilderTest.php b/src/Symfony/Component/Process/Tests/ProcessBuilderTest.php
index 0a2083f255..f3ff644bde 100644
--- a/src/Symfony/Component/Process/Tests/ProcessBuilderTest.php
+++ b/src/Symfony/Component/Process/Tests/ProcessBuilderTest.php
@@ -17,75 +17,33 @@ class ProcessBuilderTest extends \PHPUnit_Framework_TestCase
 {
     public function testInheritEnvironmentVars()
     {
-        $snapshot = $_ENV;
-        $_ENV = $expected = array('foo' => 'bar');
+        $_ENV['MY_VAR_1'] = 'foo';
 
-        $pb = new ProcessBuilder();
-        $pb->add('foo')->inheritEnvironmentVariables();
-        $proc = $pb->getProcess();
+        $proc = ProcessBuilder::create()
+            ->add('foo')
+            ->getProcess();
 
-        $this->assertNull($proc->getEnv(), '->inheritEnvironmentVariables() copies $_ENV');
+        unset($_ENV['MY_VAR_1']);
 
-        $_ENV = $snapshot;
+        $env = $proc->getEnv();
+        $this->assertArrayHasKey('MY_VAR_1', $env);
+        $this->assertEquals('foo', $env['MY_VAR_1']);
     }
 
     public function testProcessShouldInheritAndOverrideEnvironmentVars()
     {
-        $snapshot = $_ENV;
-        $_ENV = array('foo' => 'bar', 'bar' => 'baz');
-        $expected = array('foo' => 'foo', 'bar' => 'baz');
+        $_ENV['MY_VAR_1'] = 'foo';
 
-        $pb = new ProcessBuilder();
-        $pb->add('foo')->inheritEnvironmentVariables()
-            ->setEnv('foo', 'foo');
-        $proc = $pb->getProcess();
-
-        $this->assertEquals($expected, $proc->getEnv(), '->inheritEnvironmentVariables() copies $_ENV');
-
-        $_ENV = $snapshot;
-    }
-
-    public function testProcessBuilderShouldNotPassEnvArrays()
-    {
-        $snapshot = $_ENV;
-        $_ENV = array('a' => array('b', 'c'), 'd' => 'e', 'f' => 'g');
-        $expected = array('d' => 'e', 'f' => 'g');
-
-        $pb = new ProcessBuilder();
-        $pb->add('a')->inheritEnvironmentVariables()
-            ->setEnv('d', 'e');
-        $proc = $pb->getProcess();
-
-        $this->assertEquals($expected, $proc->getEnv(), '->inheritEnvironmentVariables() removes array values from $_ENV');
-
-        $_ENV = $snapshot;
-    }
-
-    public function testInheritEnvironmentVarsByDefault()
-    {
-        $pb = new ProcessBuilder();
-        $proc = $pb->add('foo')->getProcess();
-
-        $this->assertNull($proc->getEnv());
-    }
-
-    public function testNotReplaceExplicitlySetVars()
-    {
-        $snapshot = $_ENV;
-        $_ENV = array('foo' => 'bar');
-        $expected = array('foo' => 'baz');
-
-        $pb = new ProcessBuilder();
-        $pb
-            ->setEnv('foo', 'baz')
-            ->inheritEnvironmentVariables()
+        $proc = ProcessBuilder::create()
+            ->setEnv('MY_VAR_1', 'bar')
             ->add('foo')
-        ;
-        $proc = $pb->getProcess();
+            ->getProcess();
 
-        $this->assertEquals($expected, $proc->getEnv(), '->inheritEnvironmentVariables() copies $_ENV');
+        unset($_ENV['MY_VAR_1']);
 
-        $_ENV = $snapshot;
+        $env = $proc->getEnv();
+        $this->assertArrayHasKey('MY_VAR_1', $env);
+        $this->assertEquals('bar', $env['MY_VAR_1']);
     }
 
     /**