diff --git a/src/Symfony/Component/Process/Process.php b/src/Symfony/Component/Process/Process.php
index e914a4fe0113..44523b7ac293 100644
--- a/src/Symfony/Component/Process/Process.php
+++ b/src/Symfony/Component/Process/Process.php
@@ -215,9 +215,16 @@ public function run($callback = null)
      * @param callable|null $callback
      *
      * @return self
+     *
+     * @throws RuntimeException       if PHP was compiled with --enable-sigchild and the enhanced sigchild compatibility mode is not enabled
+     * @throws ProcessFailedException if the process didn't terminate successfully
      */
     public function mustRun($callback = null)
     {
+        if ($this->isSigchildEnabled() && !$this->enhanceSigchildCompatibility) {
+            throw new RuntimeException('This PHP has been compiled with --enable-sigchild. You must use setEnhanceSigchildCompatibility() to use this method.');
+        }
+
         if (0 !== $this->run($callback)) {
             throw new ProcessFailedException($this);
         }
diff --git a/src/Symfony/Component/Process/Tests/AbstractProcessTest.php b/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
index e1e173fd2c98..dbc92e264853 100644
--- a/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
+++ b/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
@@ -427,7 +427,7 @@ public function testSuccessfulMustRunHasCorrectExitCode()
     }
 
     /**
-     * @expectedException Symfony\Component\Process\Exception\ProcessFailedException
+     * @expectedException \Symfony\Component\Process\Exception\ProcessFailedException
      */
     public function testMustRunThrowsException()
     {
@@ -990,20 +990,20 @@ public function testSetNullIdleTimeoutWhileOutputIsDisabled()
     /**
      * @dataProvider provideStartMethods
      */
-    public function testStartWithACallbackAndDisabledOutput($startMethod)
+    public function testStartWithACallbackAndDisabledOutput($startMethod, $exception, $exceptionMessage)
     {
         $p = $this->getProcess('php -r "usleep(500000);"');
         $p->disableOutput();
-        $this->setExpectedException('Symfony\Component\Process\Exception\LogicException', 'Output has been disabled, enable it to allow the use of a callback.');
+        $this->setExpectedException($exception, $exceptionMessage);
         call_user_func(array($p, $startMethod), function () {});
     }
 
     public function provideStartMethods()
     {
         return array(
-            array('start'),
-            array('run'),
-            array('mustRun'),
+            array('start', 'Symfony\Component\Process\Exception\LogicException', 'Output has been disabled, enable it to allow the use of a callback.'),
+            array('run', 'Symfony\Component\Process\Exception\LogicException', 'Output has been disabled, enable it to allow the use of a callback.'),
+            array('mustRun', 'Symfony\Component\Process\Exception\LogicException', 'Output has been disabled, enable it to allow the use of a callback.'),
         );
     }
 
diff --git a/src/Symfony/Component/Process/Tests/SigchildDisabledProcessTest.php b/src/Symfony/Component/Process/Tests/SigchildDisabledProcessTest.php
index 6d10a7c6acf5..01dca1590b07 100644
--- a/src/Symfony/Component/Process/Tests/SigchildDisabledProcessTest.php
+++ b/src/Symfony/Component/Process/Tests/SigchildDisabledProcessTest.php
@@ -49,6 +49,15 @@ public function testExitCodeCommandFailed()
         parent::testExitCodeCommandFailed();
     }
 
+    /**
+     * @expectedException \Symfony\Component\Process\Exception\RuntimeException
+     * @expectedExceptionMessage This PHP has been compiled with --enable-sigchild. You must use setEnhanceSigchildCompatibility() to use this method.
+     */
+    public function testMustRun()
+    {
+        parent::testMustRun();
+    }
+
     /**
      * @expectedException \Symfony\Component\Process\Exception\RuntimeException
      * @expectedExceptionMessage This PHP has been compiled with --enable-sigchild. You must use setEnhanceSigchildCompatibility() to use this method.
@@ -232,6 +241,15 @@ public function testRunProcessWithTimeout()
         $this->markTestSkipped('Signal (required for timeout) is not supported in sigchild environment');
     }
 
+    public function provideStartMethods()
+    {
+        return array(
+            array('start', 'Symfony\Component\Process\Exception\LogicException', 'Output has been disabled, enable it to allow the use of a callback.'),
+            array('run', 'Symfony\Component\Process\Exception\LogicException', 'Output has been disabled, enable it to allow the use of a callback.'),
+            array('mustRun', 'Symfony\Component\Process\Exception\RuntimeException', 'This PHP has been compiled with --enable-sigchild. You must use setEnhanceSigchildCompatibility() to use this method.'),
+        );
+    }
+
     /**
      * {@inheritdoc}
      */