diff --git a/.travis.yml b/.travis.yml
index 7e1486d..28df844 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,7 @@ sudo: false
 
 before_script:
   - composer install
+  - php -S localhost:8000 -t tests/
 
 script:
   - vendor/bin/phpunit
diff --git a/tests/DataTest.php b/tests/DataTest.php
index a4ada48..4d096fd 100644
--- a/tests/DataTest.php
+++ b/tests/DataTest.php
@@ -129,13 +129,17 @@ public function testBuildFromFile()
      */
     public function testBuildFromUrlShouldThrowFileNotFoundException()
     {
-        $url = 'http://via.placeholder.com/x150.png';
+        $this->skipIfLocalWebServerDown();
+
+        $url = 'http://localhost:8000/unknown.png';
         Data::buildFromUrl($url);
     }
 
     public function testBuildFromUrl()
     {
-        $url = 'http://via.placeholder.com/350x150.png';
+        $this->skipIfLocalWebServerDown();
+
+        $url = 'http://localhost:8000/smile.png';
         $dataURI = Data::buildFromUrl($url);
         $this->assertInstanceOf('DataURI\Data', $dataURI);
         $this->assertEquals('image/png', $dataURI->getMimeType());
@@ -185,4 +189,21 @@ private function createEmptyFile($filename)
         fwrite($handle, '');
         fclose($handle);
     }
+
+    private function skipIfLocalWebServerDown()
+    {
+        $url = 'http://localhost:8000/';
+        $ch = curl_init($url);
+        curl_setopt($ch, CURLOPT_HEADER, true);
+        curl_setopt($ch, CURLOPT_NOBODY, true);
+        curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
+        curl_setopt($ch, CURLOPT_TIMEOUT,10);
+        curl_exec($ch);
+        $httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+        curl_close($ch);
+
+        if (0 === $httpcode) {
+            $this->markTestSkipped('The local web server is down. Run it with `php -S localhost:8000 -t tests/`.');
+        }
+    }
 }