diff --git a/src/Symfony/Component/Process/Process.php b/src/Symfony/Component/Process/Process.php
index c7a1cf2a44..9f999c2530 100644
--- a/src/Symfony/Component/Process/Process.php
+++ b/src/Symfony/Component/Process/Process.php
@@ -418,6 +418,9 @@ class Process
         if ($this->isRunning()) {
             throw new RuntimeException('Disabling output while the process is running is not possible.');
         }
+        if (null !== $this->idleTimeout) {
+            throw new LogicException('Output can not be disabled while an idle timeout is set.');
+        }
 
         $this->outputDisabled = true;
 
@@ -870,6 +873,10 @@ class Process
      */
     public function setIdleTimeout($timeout)
     {
+        if (null !== $timeout && $this->outputDisabled) {
+            throw new LogicException('Idle timeout can not be set while the output is disabled.');
+        }
+
         $this->idleTimeout = $this->validateTimeout($timeout);
 
         return $this;
diff --git a/src/Symfony/Component/Process/Tests/AbstractProcessTest.php b/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
index 75981c97d3..f15260d729 100644
--- a/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
+++ b/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
@@ -550,7 +550,7 @@ abstract class AbstractProcessTest extends \PHPUnit_Framework_TestCase
     {
         $process = $this->getProcess('sleep 3');
         $process->setTimeout(10);
-        $process->setIdleTimeout(1);
+        $process->setIdleTimeout(0.5);
 
         try {
             $process->run();
@@ -559,7 +559,7 @@ abstract class AbstractProcessTest extends \PHPUnit_Framework_TestCase
         } catch (ProcessTimedOutException $ex) {
             $this->assertTrue($ex->isIdleTimeout());
             $this->assertFalse($ex->isGeneralTimeout());
-            $this->assertEquals(1.0, $ex->getExceededTimeout());
+            $this->assertEquals(0.5, $ex->getExceededTimeout());
         }
     }
 
@@ -568,9 +568,9 @@ abstract class AbstractProcessTest extends \PHPUnit_Framework_TestCase
      */
     public function testIdleTimeoutNotExceededWhenOutputIsSent()
     {
-        $process = $this->getProcess('echo "foo" && sleep 1 && echo "foo" && sleep 1 && echo "foo" && sleep 1 && echo "foo" && sleep 5');
-        $process->setTimeout(5);
-        $process->setIdleTimeout(3);
+        $process = $this->getProcess('echo "foo" && sleep 1 && echo "foo" && sleep 1 && echo "foo" && sleep 1');
+        $process->setTimeout(2);
+        $process->setIdleTimeout(1.5);
 
         try {
             $process->run();
@@ -578,14 +578,14 @@ abstract class AbstractProcessTest extends \PHPUnit_Framework_TestCase
         } catch (ProcessTimedOutException $ex) {
             $this->assertTrue($ex->isGeneralTimeout());
             $this->assertFalse($ex->isIdleTimeout());
-            $this->assertEquals(5.0, $ex->getExceededTimeout());
+            $this->assertEquals(2, $ex->getExceededTimeout());
         }
     }
 
     public function testStartAfterATimeout()
     {
         $process = $this->getProcess('php -r "while (true) {echo \'\'; usleep(1000); }"');
-        $process->setTimeout(0.1);
+        $process->setTimeout(0.2);
         try {
             $process->run();
             $this->fail('An exception should have been raised.');
@@ -593,7 +593,7 @@ abstract class AbstractProcessTest extends \PHPUnit_Framework_TestCase
 
         }
         $process->start();
-        usleep(10000);
+        usleep(1000);
         $process->stop();
     }
 
@@ -737,6 +737,29 @@ abstract class AbstractProcessTest extends \PHPUnit_Framework_TestCase
         $p->disableOutput();
     }
 
+    public function testDisableOutputWhileIdleTimeoutIsSet()
+    {
+        $process = $this->getProcess('sleep 3');
+        $process->setIdleTimeout(1);
+        $this->setExpectedException('Symfony\Component\Process\Exception\LogicException', 'Output can not be disabled while an idle timeout is set.');
+        $process->disableOutput();
+    }
+
+    public function testSetIdleTimeoutWhileOutputIsDisabled()
+    {
+        $process = $this->getProcess('sleep 3');
+        $process->disableOutput();
+        $this->setExpectedException('Symfony\Component\Process\Exception\LogicException', 'Idle timeout can not be set while the output is disabled.');
+        $process->setIdleTimeout(1);
+    }
+
+    public function testSetNullIdleTimeoutWhileOutputIsDisabled()
+    {
+        $process = $this->getProcess('sleep 3');
+        $process->disableOutput();
+        $process->setIdleTimeout(null);
+    }
+
     /**
      * @dataProvider provideStartMethods
      */