diff --git a/src/Composer/Command/InitCommand.php b/src/Composer/Command/InitCommand.php
index 469df7ffb..e06b670b9 100644
--- a/src/Composer/Command/InitCommand.php
+++ b/src/Composer/Command/InitCommand.php
@@ -869,10 +869,10 @@ EOT
                 return array($name, $requiredVersion ?: '*');
             }
 
-            // Check whether the PHP version was the problem
+            // Check whether the package requirements were the problem
             if (true !== $ignorePlatformReqs && ($candidate = $versionSelector->findBestCandidate($name, $requiredVersion, $preferredStability, true))) {
                 throw new \InvalidArgumentException(sprintf(
-                    'Package %s%s has a PHP requirement incompatible with your PHP version, PHP extensions and Composer version' . $this->getPlatformExceptionDetails($candidate, $platformRepo),
+                    'Package %s%s has requirements incompatible with your PHP version, PHP extensions and Composer version' . $this->getPlatformExceptionDetails($candidate, $platformRepo),
                     $name,
                     $requiredVersion ? ' at version '.$requiredVersion : ''
                 ));
diff --git a/src/Composer/Package/Version/VersionSelector.php b/src/Composer/Package/Version/VersionSelector.php
index 046cccde6..79972999a 100644
--- a/src/Composer/Package/Version/VersionSelector.php
+++ b/src/Composer/Package/Version/VersionSelector.php
@@ -82,14 +82,20 @@ class VersionSelector
                 $reqs = $pkg->getRequires();
 
                 foreach ($reqs as $name => $link) {
-                    if (!in_array($name, $ignorePlatformReqs, true) && isset($platformConstraints[$name])) {
-                        foreach ($platformConstraints[$name] as $constraint) {
-                            if ($link->getConstraint()->matches($constraint)) {
-                                continue 2;
+                    if (!in_array($name, $ignorePlatformReqs, true)) {
+                        if (isset($platformConstraints[$name])) {
+                            foreach ($platformConstraints[$name] as $constraint) {
+                                if ($link->getConstraint()->matches($constraint)) {
+                                    continue 2;
+                                }
                             }
-                        }
 
-                        return false;
+                            return false;
+                        } elseif (PlatformRepository::isPlatformPackage($name)) {
+                            // Package requires a platform package that is unknown on current platform.
+                            // It means that current platform cannot validate this constraint and so package is not installable.
+                            return false;
+                        }
                     }
                 }
 
diff --git a/tests/Composer/Test/Package/Version/VersionSelectorTest.php b/tests/Composer/Test/Package/Version/VersionSelectorTest.php
index abe77ba0f..e02470e6b 100644
--- a/tests/Composer/Test/Package/Version/VersionSelectorTest.php
+++ b/tests/Composer/Test/Package/Version/VersionSelectorTest.php
@@ -100,6 +100,31 @@ class VersionSelectorTest extends TestCase
         $this->assertSame($package2, $best, 'Latest version should be returned when ignoring platform reqs (2.0.0)');
     }
 
+    public function testLatestVersionIsReturnedThatMatchesPlatformExt()
+    {
+        $packageName = 'foobar';
+
+        $platform = new PlatformRepository();
+        $repositorySet = $this->createMockRepositorySet();
+        $versionSelector = new VersionSelector($repositorySet, $platform);
+
+        $parser = new VersionParser;
+        $package1 = $this->createPackage('1.0.0');
+        $package2 = $this->createPackage('2.0.0');
+        $package2->setRequires(array('ext-barfoo' => new Link($packageName, 'ext-barfoo', $parser->parseConstraints('*'), Link::TYPE_REQUIRE, '*')));
+        $packages = array($package1, $package2);
+
+        $repositorySet->expects($this->any())
+            ->method('findPackages')
+            ->with($packageName, null)
+            ->will($this->returnValue($packages));
+
+        $best = $versionSelector->findBestCandidate($packageName);
+        $this->assertSame($package1, $best, 'Latest version not requiring ext-barfoo should be returned (1.0.0)');
+        $best = $versionSelector->findBestCandidate($packageName, null, 'stable', true);
+        $this->assertSame($package2, $best, 'Latest version should be returned when ignoring platform reqs (2.0.0)');
+    }
+
     public function testLatestVersionIsReturnedThatMatchesComposerRequirements()
     {
         $packageName = 'foobar';