diff --git a/src/Symfony/Component/Process/Process.php b/src/Symfony/Component/Process/Process.php
index 822671467b..2ccad53d77 100644
--- a/src/Symfony/Component/Process/Process.php
+++ b/src/Symfony/Component/Process/Process.php
@@ -880,7 +880,8 @@ class Process
      *
      * @return self The current Process instance
      *
-     * @throws LogicException In case the process is running
+     * @throws LogicException           In case the process is running
+     * @throws InvalidArgumentException In case the argument is invalid
      */
     public function setStdin($stdin)
     {
@@ -888,7 +889,7 @@ class Process
             throw new LogicException('STDIN can not be set while the process is running.');
         }
 
-        $this->stdin = $stdin;
+        $this->stdin = ProcessUtils::validateInput(sprintf('%s::%s', __CLASS__, __FUNCTION__), $stdin);
 
         return $this;
     }
diff --git a/src/Symfony/Component/Process/ProcessBuilder.php b/src/Symfony/Component/Process/ProcessBuilder.php
index 3e3eed8920..ef1fefc3d9 100644
--- a/src/Symfony/Component/Process/ProcessBuilder.php
+++ b/src/Symfony/Component/Process/ProcessBuilder.php
@@ -148,13 +148,15 @@ class ProcessBuilder
     /**
      * Sets the input of the process.
      *
-     * @param string $stdin The input as a string
+     * @param string|null $stdin The input as a string
      *
      * @return ProcessBuilder
+     *
+     * @throws InvalidArgumentException In case the argument is invalid
      */
     public function setInput($stdin)
     {
-        $this->stdin = $stdin;
+        $this->stdin = ProcessUtils::validateInput(sprintf('%s::%s', __CLASS__, __FUNCTION__), $stdin);
 
         return $this;
     }
diff --git a/src/Symfony/Component/Process/ProcessUtils.php b/src/Symfony/Component/Process/ProcessUtils.php
index 5317cd0883..441522d388 100644
--- a/src/Symfony/Component/Process/ProcessUtils.php
+++ b/src/Symfony/Component/Process/ProcessUtils.php
@@ -11,6 +11,8 @@
 
 namespace Symfony\Component\Process;
 
+use Symfony\Component\Process\Exception\InvalidArgumentException;
+
 /**
  * ProcessUtils is a bunch of utility methods.
  *
@@ -72,6 +74,29 @@ class ProcessUtils
         return escapeshellarg($argument);
     }
 
+    /**
+     * Validates and normalized a Process input
+     *
+     * @param string $caller The name of method call that validates the input
+     * @param mixed  $input  The input to validate
+     *
+     * @return string The validated input
+     *
+     * @throws InvalidArgumentException In case the input is not valid
+     */
+    public static function validateInput($caller, $input)
+    {
+        if (null !== $input) {
+            if (is_scalar($input) || (is_object($input) && method_exists($input, '__toString'))) {
+                return (string) $input;
+            }
+
+            throw new InvalidArgumentException(sprintf('%s only accepts strings.', $caller));
+        }
+
+        return $input;
+    }
+
     private static function isSurroundedBy($arg, $char)
     {
         return 2 < strlen($arg) && $char === $arg[0] && $char === $arg[strlen($arg) - 1];
diff --git a/src/Symfony/Component/Process/Tests/AbstractProcessTest.php b/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
index 50d80cae77..91b8aca20d 100644
--- a/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
+++ b/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
@@ -171,6 +171,47 @@ abstract class AbstractProcessTest extends \PHPUnit_Framework_TestCase
         $process->stop();
     }
 
+    /**
+     * @dataProvider provideInvalidStdinValues
+     * @expectedException \Symfony\Component\Process\Exception\InvalidArgumentException
+     * @expectedExceptionMessage Symfony\Component\Process\Process::setStdin only accepts strings.
+     */
+    public function testInvalidStdin($value)
+    {
+        $process = $this->getProcess('php -v');
+        $process->setStdin($value);
+    }
+
+    public function provideInvalidStdinValues()
+    {
+        return array(
+            array(array()),
+            array(new NonStringifiable()),
+            array(fopen('php://temporary', 'w')),
+        );
+    }
+
+    /**
+     * @dataProvider provideStdinValues
+     */
+    public function testValidStdin($expected, $value)
+    {
+        $process = $this->getProcess('php -v');
+        $process->setStdin($value);
+        $this->assertSame($expected, $process->getStdin());
+    }
+
+    public function provideStdinValues()
+    {
+        return array(
+            array(null, null),
+            array('24.5', 24.5),
+            array('input data', 'input data'),
+            // to maintain BC, supposed to be removed in 3.0
+            array('stringifiable', new Stringifiable()),
+        );
+    }
+
     public function chainedCommandsOutputProvider()
     {
         if (defined('PHP_WINDOWS_VERSION_BUILD')) {
@@ -813,3 +854,15 @@ abstract class AbstractProcessTest extends \PHPUnit_Framework_TestCase
      */
     abstract protected function getProcess($commandline, $cwd = null, array $env = null, $stdin = null, $timeout = 60, array $options = array());
 }
+
+class Stringifiable
+{
+    public function __toString()
+    {
+        return 'stringifiable';
+    }
+}
+
+class NonStringifiable
+{
+}
diff --git a/src/Symfony/Component/Process/Tests/ProcessBuilderTest.php b/src/Symfony/Component/Process/Tests/ProcessBuilderTest.php
index d0611f0b41..70245e0a42 100644
--- a/src/Symfony/Component/Process/Tests/ProcessBuilderTest.php
+++ b/src/Symfony/Component/Process/Tests/ProcessBuilderTest.php
@@ -197,4 +197,14 @@ class ProcessBuilderTest extends \PHPUnit_Framework_TestCase
             $this->assertEquals("'/usr/bin/php'", $process->getCommandLine());
         }
     }
+
+    /**
+     * @expectedException \Symfony\Component\Process\Exception\InvalidArgumentException
+     * @expectedExceptionMessage Symfony\Component\Process\ProcessBuilder::setInput only accepts strings.
+     */
+    public function testInvalidInput()
+    {
+        $builder = ProcessBuilder::create();
+        $builder->setInput(array());
+    }
 }