diff --git a/src/Symfony/Component/Routing/Generator/UrlGenerator.php b/src/Symfony/Component/Routing/Generator/UrlGenerator.php
index b87f4bb5c45f7..ae677c8faef88 100644
--- a/src/Symfony/Component/Routing/Generator/UrlGenerator.php
+++ b/src/Symfony/Component/Routing/Generator/UrlGenerator.php
@@ -222,16 +222,18 @@ protected function doGenerate($variables, $defaults, $requirements, $tokens, $pa
             }
         }
 
-        if ((self::ABSOLUTE_URL === $referenceType || self::NETWORK_PATH === $referenceType) && !empty($host)) {
-            $port = '';
-            if ('http' === $scheme && 80 != $this->context->getHttpPort()) {
-                $port = ':'.$this->context->getHttpPort();
-            } elseif ('https' === $scheme && 443 != $this->context->getHttpsPort()) {
-                $port = ':'.$this->context->getHttpsPort();
-            }
+        if (self::ABSOLUTE_URL === $referenceType || self::NETWORK_PATH === $referenceType) {
+            if ('' != $host || ('' != $scheme && 'http' !== $scheme && 'https' !== $scheme)) {
+                $port = '';
+                if ('http' === $scheme && 80 != $this->context->getHttpPort()) {
+                    $port = ':'.$this->context->getHttpPort();
+                } elseif ('https' === $scheme && 443 != $this->context->getHttpsPort()) {
+                    $port = ':'.$this->context->getHttpsPort();
+                }
 
-            $schemeAuthority = self::NETWORK_PATH === $referenceType ? '//' : "$scheme://";
-            $schemeAuthority .= $host.$port;
+                $schemeAuthority = self::NETWORK_PATH === $referenceType || '' == $scheme ? '//' : "$scheme://";
+                $schemeAuthority .= $host.$port;
+            }
         }
 
         if (self::RELATIVE_PATH === $referenceType) {
diff --git a/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php b/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
index 7f64a1f378326..a4d754cb14a6c 100644
--- a/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
+++ b/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
@@ -480,28 +480,27 @@ public function testHostIsCaseInsensitive()
 
     public function testDefaultHostIsUsedWhenContextHostIsEmpty()
     {
-        $routes = $this->getRoutes('test', new Route('/route', ['domain' => 'my.fallback.host'], ['domain' => '.+'], [], '{domain}', ['http']));
+        $routes = $this->getRoutes('test', new Route('/path', ['domain' => 'my.fallback.host'], ['domain' => '.+'], [], '{domain}'));
 
         $generator = $this->getGenerator($routes);
         $generator->getContext()->setHost('');
 
-        $this->assertSame('http://my.fallback.host/app.php/route', $generator->generate('test', [], UrlGeneratorInterface::ABSOLUTE_URL));
+        $this->assertSame('http://my.fallback.host/app.php/path', $generator->generate('test', [], UrlGeneratorInterface::ABSOLUTE_URL));
     }
 
-    public function testDefaultHostIsUsedWhenContextHostIsEmptyAndSchemeIsNot()
+    public function testDefaultHostIsUsedWhenContextHostIsEmptyAndPathReferenceType()
     {
-        $routes = $this->getRoutes('test', new Route('/route', ['domain' => 'my.fallback.host'], ['domain' => '.+'], [], '{domain}', ['http', 'https']));
+        $routes = $this->getRoutes('test', new Route('/path', ['domain' => 'my.fallback.host'], ['domain' => '.+'], [], '{domain}'));
 
         $generator = $this->getGenerator($routes);
         $generator->getContext()->setHost('');
-        $generator->getContext()->setScheme('https');
 
-        $this->assertSame('https://my.fallback.host/app.php/route', $generator->generate('test', [], UrlGeneratorInterface::ABSOLUTE_URL));
+        $this->assertSame('//my.fallback.host/app.php/path', $generator->generate('test', [], UrlGeneratorInterface::ABSOLUTE_PATH));
     }
 
-    public function testAbsoluteUrlFallbackToRelativeIfHostIsEmptyAndSchemeIsNot()
+    public function testAbsoluteUrlFallbackToPathIfHostIsEmptyAndSchemeIsHttp()
     {
-        $routes = $this->getRoutes('test', new Route('/route', [], [], [], '', ['http', 'https']));
+        $routes = $this->getRoutes('test', new Route('/route'));
 
         $generator = $this->getGenerator($routes);
         $generator->getContext()->setHost('');
@@ -510,6 +509,39 @@ public function testAbsoluteUrlFallbackToRelativeIfHostIsEmptyAndSchemeIsNot()
         $this->assertSame('/app.php/route', $generator->generate('test', [], UrlGeneratorInterface::ABSOLUTE_URL));
     }
 
+    public function testAbsoluteUrlFallbackToNetworkIfSchemeIsEmptyAndHostIsNot()
+    {
+        $routes = $this->getRoutes('test', new Route('/path'));
+
+        $generator = $this->getGenerator($routes);
+        $generator->getContext()->setHost('example.com');
+        $generator->getContext()->setScheme('');
+
+        $this->assertSame('//example.com/app.php/path', $generator->generate('test', [], UrlGeneratorInterface::ABSOLUTE_URL));
+    }
+
+    public function testAbsoluteUrlFallbackToPathIfSchemeAndHostAreEmpty()
+    {
+        $routes = $this->getRoutes('test', new Route('/path'));
+
+        $generator = $this->getGenerator($routes);
+        $generator->getContext()->setHost('');
+        $generator->getContext()->setScheme('');
+
+        $this->assertSame('/app.php/path', $generator->generate('test', [], UrlGeneratorInterface::ABSOLUTE_URL));
+    }
+
+    public function testAbsoluteUrlWithNonHttpSchemeAndEmptyHost()
+    {
+        $routes = $this->getRoutes('test', new Route('/path', [], [], [], '', ['file']));
+
+        $generator = $this->getGenerator($routes);
+        $generator->getContext()->setBaseUrl('');
+        $generator->getContext()->setHost('');
+
+        $this->assertSame('file:///path', $generator->generate('test', [], UrlGeneratorInterface::ABSOLUTE_URL));
+    }
+
     public function testGenerateNetworkPath()
     {
         $routes = $this->getRoutes('test', new Route('/{name}', [], [], [], '{locale}.example.com', ['http']));