diff --git a/src/PackageDiff.php b/src/PackageDiff.php
index fc4691f..301b490 100644
--- a/src/PackageDiff.php
+++ b/src/PackageDiff.php
@@ -130,11 +130,12 @@ private function getFileContents($path)
 
         $output = array();
         @exec(sprintf('git show %s 2>&1', escapeshellarg($path)), $output, $exit);
+        $outputString = implode("\n", $output);
 
         if (0 !== $exit) {
-            throw new \RuntimeException(sprintf('Could not open file %s or find it in git as %s', $originalPath, $path));
+            throw new \RuntimeException(sprintf('Could not open file %s or find it in git as %s: %s', $originalPath, $path, $outputString));
         }
 
-        return implode("\n", $output);
+        return $outputString;
     }
 }
diff --git a/src/Url/GitGenerator.php b/src/Url/GitGenerator.php
index 5aa4b68..5b0f722 100644
--- a/src/Url/GitGenerator.php
+++ b/src/Url/GitGenerator.php
@@ -11,7 +11,7 @@ abstract class GitGenerator implements UrlGenerator
      */
     public function supportsPackage(PackageInterface $package)
     {
-        return false !== strpos($package->getSourceUrl(), $this->getDomain());
+        return false !== strpos((string) $package->getSourceUrl(), $this->getDomain());
     }
 
     /**
diff --git a/tests/Command/DiffCommandTest.php b/tests/Command/DiffCommandTest.php
index f672348..ad40b31 100644
--- a/tests/Command/DiffCommandTest.php
+++ b/tests/Command/DiffCommandTest.php
@@ -7,6 +7,7 @@
 use Composer\DependencyResolver\Operation\UninstallOperation;
 use Composer\DependencyResolver\Operation\UpdateOperation;
 use IonBazan\ComposerDiff\Command\DiffCommand;
+use IonBazan\ComposerDiff\Tests\Integration\ComposerApplication;
 use IonBazan\ComposerDiff\Tests\TestCase;
 use Symfony\Component\Console\Tester\CommandTester;
 
@@ -20,7 +21,10 @@ class DiffCommandTest extends TestCase
     public function testItGeneratesReportInGivenFormat($expectedOutput, array $options)
     {
         $diff = $this->getMockBuilder('IonBazan\ComposerDiff\PackageDiff')->getMock();
-        $tester = new CommandTester(new DiffCommand($diff, array('gitlab2.org')));
+        $application = new ComposerApplication();
+        $command = new DiffCommand($diff, array('gitlab2.org'));
+        $command->setApplication($application);
+        $tester = new CommandTester($command);
         $diff->expects($this->once())
             ->method('getPackageDiff')
             ->with($this->isType('string'), $this->isType('string'), false, false)
@@ -49,7 +53,10 @@ public function testItGeneratesReportInGivenFormat($expectedOutput, array $optio
     public function testStrictMode($exitCode, array $prodOperations, array $devOperations)
     {
         $diff = $this->getMockBuilder('IonBazan\ComposerDiff\PackageDiff')->getMock();
-        $tester = new CommandTester(new DiffCommand($diff, array('gitlab2.org')));
+        $application = new ComposerApplication();
+        $command = new DiffCommand($diff, array('gitlab2.org'));
+        $command->setApplication($application);
+        $tester = new CommandTester($command);
         $diff->expects($this->exactly(2))
             ->method('getPackageDiff')
             ->with($this->isType('string'), $this->isType('string'), $this->isType('boolean'), false)
diff --git a/tests/Integration/DiffCommandTest.php b/tests/Integration/DiffCommandTest.php
index 43bacc6..71e6cc3 100644
--- a/tests/Integration/DiffCommandTest.php
+++ b/tests/Integration/DiffCommandTest.php
@@ -24,7 +24,10 @@ class DiffCommandTest extends TestCase
      */
     public function testCommand($expectedOutput, array $input)
     {
-        $tester = new CommandTester(new DiffCommand(new PackageDiff()));
+        $application = new ComposerApplication();
+        $command = new DiffCommand(new PackageDiff());
+        $command->setApplication($application);
+        $tester = new CommandTester($command);
         $result = $tester->execute($input);
         $this->assertSame(0, $result);
         $this->assertSame($expectedOutput, $tester->getDisplay());