diff --git a/src/Composer/Installer.php b/src/Composer/Installer.php
index dad53d023..e1417019f 100644
--- a/src/Composer/Installer.php
+++ b/src/Composer/Installer.php
@@ -250,9 +250,14 @@ class Installer
                     }
                 }
 
+                $platformReqs = $this->extractPlatformRequirements($this->package->getRequires());
+                $platformDevReqs = $this->devMode ? $this->extractPlatformRequirements($this->package->getDevRequires()) : array();
+
                 $updatedLock = $this->locker->setLockData(
                     array_diff($localRepo->getPackages(), (array) $devPackages),
                     $devPackages,
+                    $platformReqs,
+                    $platformDevReqs,
                     $aliases,
                     $this->package->getMinimumStability(),
                     $this->package->getStabilityFlags()
@@ -350,6 +355,10 @@ class Installer
                 $constraint->setPrettyString($package->getPrettyVersion());
                 $request->install($package->getName(), $constraint);
             }
+
+            foreach ($this->locker->getPlatformRequirements($withDevReqs) as $link) {
+                $request->install($link->getTarget(), $link->getConstraint());
+            }
         } else {
             $this->io->write('<info>Installing dependencies'.($withDevReqs?' (including require-dev)':'').'</info>');
 
@@ -675,6 +684,17 @@ class Installer
         return false;
     }
 
+    private function extractPlatformRequirements($links) {
+        $platformReqs = array();
+        foreach ($links as $link) {
+            if (preg_match('{^(?:php(?:-64bit)?|(?:ext|lib)-[^/]+)$}i', $link->getTarget())) {
+                $platformReqs[$link->getTarget()] = $link->getPrettyConstraint();
+            }
+        }
+
+        return $platformReqs;
+    }
+
     /**
      * Adds all dependencies of the update whitelist to the whitelist, too.
      *
diff --git a/src/Composer/Package/Locker.php b/src/Composer/Package/Locker.php
index 424983787..e8390816a 100644
--- a/src/Composer/Package/Locker.php
+++ b/src/Composer/Package/Locker.php
@@ -20,6 +20,7 @@ use Composer\Package\AliasPackage;
 use Composer\Repository\ArrayRepository;
 use Composer\Package\Dumper\ArrayDumper;
 use Composer\Package\Loader\ArrayLoader;
+use Composer\Package\Version\VersionParser;
 
 /**
  * Reads/writes project lockfile (composer.lock).
@@ -178,6 +179,41 @@ class Locker
         return $packages;
     }
 
+    /**
+     * Returns the platform requirements stored in the lock file
+     *
+     * @param bool $withDevReqs if true, the platform requirements from the require-dev block are also returned
+     * @return \Composer\Package\Link[]
+     */
+    public function getPlatformRequirements($withDevReqs = false)
+    {
+        $lockData = $this->getLockData();
+        $versionParser = new VersionParser();
+        $requirements = array();
+
+        if (!empty($lockData['platform'])) {
+            $requirements = $versionParser->parseLinks(
+                '__ROOT__',
+                '1.0.0',
+                'requires',
+                isset($lockData['platform']) ? $lockData['platform'] : array()
+            );
+        }
+
+        if ($withDevReqs && !empty($lockData['platform-dev'])) {
+            $devRequirements = $versionParser->parseLinks(
+                '__ROOT__',
+                '1.0.0',
+                'requires',
+                isset($lockData['platform-dev']) ? $lockData['platform-dev'] : array()
+            );
+
+            $requirements = array_merge($requirements, $devRequirements);
+        }
+
+        return $requirements;
+    }
+
     public function getMinimumStability()
     {
         $lockData = $this->getLockData();
@@ -217,13 +253,15 @@ class Locker
      *
      * @param array  $packages         array of packages
      * @param mixed  $devPackages      array of dev packages or null if installed without --dev
+     * @param array  $platformReqs     array of package name => constraint for required platform packages
+     * @param mixed  $platformDevReqs  array of package name => constraint for dev-required platform packages
      * @param array  $aliases          array of aliases
      * @param string $minimumStability
      * @param array  $stabilityFlags
      *
      * @return bool
      */
-    public function setLockData(array $packages, $devPackages, array $aliases, $minimumStability, array $stabilityFlags)
+    public function setLockData(array $packages, $devPackages, array $platformReqs, $platformDevReqs, array $aliases, $minimumStability, array $stabilityFlags)
     {
         $lock = array(
             'hash' => $this->hash,
@@ -258,6 +296,9 @@ class Locker
             return false;
         }
 
+        $lock['platform'] = $platformReqs;
+        $lock['platform-dev'] = $platformDevReqs;
+
         if (!$this->isLocked() || $lock !== $this->getLockData()) {
             $this->lockFile->write($lock);
             $this->lockDataCache = null;
diff --git a/tests/Composer/Test/Fixtures/installer/install-dev-using-dist.test b/tests/Composer/Test/Fixtures/installer/install-dev-using-dist.test
index 69b56fa1d..91e30c546 100644
--- a/tests/Composer/Test/Fixtures/installer/install-dev-using-dist.test
+++ b/tests/Composer/Test/Fixtures/installer/install-dev-using-dist.test
@@ -46,7 +46,9 @@ install --prefer-dist
     "minimum-stability": "dev",
     "stability-flags": {
         "a/a": 20
-    }
+    },
+    "platform": [],
+    "platform-dev": []
 }
 --EXPECT--
 Installing a/a (dev-master)
diff --git a/tests/Composer/Test/Fixtures/installer/update-alias-lock.test b/tests/Composer/Test/Fixtures/installer/update-alias-lock.test
index f30f3a17f..46ce63b75 100644
--- a/tests/Composer/Test/Fixtures/installer/update-alias-lock.test
+++ b/tests/Composer/Test/Fixtures/installer/update-alias-lock.test
@@ -63,7 +63,9 @@ update
     "packages-dev": null,
     "aliases": [],
     "minimum-stability": "dev",
-    "stability-flags": []
+    "stability-flags": [],
+    "platform": [],
+    "platform-dev": []
 }
 --EXPECT--
 Updating a/a (dev-master 1234) to a/a (dev-master master)
\ No newline at end of file
diff --git a/tests/Composer/Test/Fixtures/installer/updating-dev-updates-url-and-reference.test b/tests/Composer/Test/Fixtures/installer/updating-dev-updates-url-and-reference.test
index 272dfc819..ee92652e6 100644
--- a/tests/Composer/Test/Fixtures/installer/updating-dev-updates-url-and-reference.test
+++ b/tests/Composer/Test/Fixtures/installer/updating-dev-updates-url-and-reference.test
@@ -56,7 +56,9 @@ update
     "packages-dev": null,
     "aliases": [],
     "minimum-stability": "dev",
-    "stability-flags": {"a/a":20}
+    "stability-flags": {"a/a":20},
+    "platform": [],
+    "platform-dev": []
 }
 --EXPECT--
 Updating a/a (dev-master oldref) to a/a (dev-master newref)
diff --git a/tests/Composer/Test/Package/LockerTest.php b/tests/Composer/Test/Package/LockerTest.php
index b9b1950c9..35cb90e04 100644
--- a/tests/Composer/Test/Package/LockerTest.php
+++ b/tests/Composer/Test/Package/LockerTest.php
@@ -171,9 +171,11 @@ class LockerTest extends \PHPUnit_Framework_TestCase
                 'aliases' => array(),
                 'minimum-stability' => 'dev',
                 'stability-flags' => array(),
+                'platform' => array(),
+                'platform-dev' => array(),
             ));
 
-        $locker->setLockData(array($package1, $package2), array(), array(), 'dev', array());
+        $locker->setLockData(array($package1, $package2), array(), array(), array(), array(), 'dev', array());
     }
 
     public function testLockBadPackages()
@@ -192,7 +194,7 @@ class LockerTest extends \PHPUnit_Framework_TestCase
 
         $this->setExpectedException('LogicException');
 
-        $locker->setLockData(array($package1), array(), array(), 'dev', array());
+        $locker->setLockData(array($package1), array(), array(), array(), array(), 'dev', array());
     }
 
     public function testIsFresh()