diff --git a/src/Helper/ProcessHelper.php b/src/Helper/ProcessHelper.php
index 20d35969..89e780bf 100644
--- a/src/Helper/ProcessHelper.php
+++ b/src/Helper/ProcessHelper.php
@@ -78,7 +78,7 @@ public function runCommand($command, $allowFailures = false, $callback = null)
         $process->run($callback);
 
         if (!$process->isSuccessful() && !$allowFailures) {
-            throw new \RuntimeException($process->getErrorOutput());
+            throw new \RuntimeException(trim($process->getErrorOutput()), (int) $process->getExitCode());
         }
 
         return trim($process->getOutput());
diff --git a/tests/Helper/GitHelperTest.php b/tests/Helper/GitHelperTest.php
index 2210d4ab..559c80ad 100644
--- a/tests/Helper/GitHelperTest.php
+++ b/tests/Helper/GitHelperTest.php
@@ -102,15 +102,14 @@ public function returns_false_when_top_git_dir_was_expected()
     }
 
     /**
-     * @test
      * @runInSeparateProcess
      */
-    public function returns_false_for_non_git_dir()
+    public function testThrowExceptionForNonGitDir()
     {
         chdir(sys_get_temp_dir());
 
+        $this->setExpectedExceptionRegExp('\RuntimeException', '#^fatal: Not a git repository \(or any of the parent directories\): \.git$#', 128);
         $this->assertFalse($this->git->isGitDir());
-        $this->assertFalse($this->git->isGitDir(false));
     }
 
     /**