diff --git a/PHPCI/Helper/Diff.php b/PHPCI/Helper/Diff.php
index e50c7eaf..5dcb5388 100644
--- a/PHPCI/Helper/Diff.php
+++ b/PHPCI/Helper/Diff.php
@@ -26,11 +26,15 @@ class Diff
      */
     public function getLinePositions($diff)
     {
+        if (empty($diff)) {
+            return null;
+        }
+
         $rtn = array();
 
         $diffLines = explode(PHP_EOL, $diff);
 
-        while (1) {
+        while (count($diffLines)) {
             $line = array_shift($diffLines);
 
             if (substr($line, 0, 2) == '@@') {
diff --git a/PHPCI/Model/Build/GithubBuild.php b/PHPCI/Model/Build/GithubBuild.php
index 1482f1c0..4d61b9d6 100644
--- a/PHPCI/Model/Build/GithubBuild.php
+++ b/PHPCI/Model/Build/GithubBuild.php
@@ -211,7 +211,7 @@ class GithubBuild extends RemoteGitBuild
         } else {
             $commitId = $this->getCommitId();
             $compare = $commitId == 'Manual' ? 'HEAD' : $commitId;
-            $builder->executeCommand('cd %s && git diff %s^! "%s"', $path, $compare, $file);
+            $builder->executeCommand('cd %s && git diff %s^^ "%s"', $path, $compare, $file);
         }
 
         $builder->logExecOutput(true);