diff --git a/src/applications/differential/storage/diff/DifferentialDiff.php b/src/applications/differential/storage/diff/DifferentialDiff.php
index 1e245b4bfb..4ccac47a0a 100644
--- a/src/applications/differential/storage/diff/DifferentialDiff.php
+++ b/src/applications/differential/storage/diff/DifferentialDiff.php
@@ -187,10 +187,10 @@ final class DifferentialDiff extends DifferentialDAO {
               // Search also backwards for short lines.
               foreach (array(-1, 1) as $direction) {
                 $offset = $direction;
-                $orig_code = idx($files[$file], $orig_line + $offset);
                 while (!isset($copies[$line + $offset]) &&
                     isset($added[$line + $offset]) &&
-                    $orig_code === $added[$line + $offset]) {
+                    idx($files[$file], $orig_line + $offset) ===
+                      $added[$line + $offset]) {
                   $lengths["$orig_line:$file"]++;
                   $offset += $direction;
                 }
diff --git a/src/applications/differential/storage/hunk/DifferentialHunk.php b/src/applications/differential/storage/hunk/DifferentialHunk.php
index b53a6955f2..7892afdcab 100644
--- a/src/applications/differential/storage/hunk/DifferentialHunk.php
+++ b/src/applications/differential/storage/hunk/DifferentialHunk.php
@@ -33,7 +33,7 @@ final class DifferentialHunk extends DifferentialDAO {
         continue;
       }
       if ($diff_line[0] == '+') {
-        $lines[$n] = substr($diff_line, 1);
+        $lines[$n] = (string)substr($diff_line, 1); // substr('+', 1) === false
       }
       if ($diff_line[0] != '-') {
         $n++;