diff --git a/src/IO/Compare/CompareDirectory.php b/src/IO/Compare/CompareDirectory.php
index 10d37ad..41caf73 100644
--- a/src/IO/Compare/CompareDirectory.php
+++ b/src/IO/Compare/CompareDirectory.php
@@ -13,7 +13,7 @@ class CompareDirectory extends Directory
     public function diff(): array
     {
         $differences = [];
-        $this->each(function (SplFileInfo $file, SplFileInfo $otherPath) use ($differences) {
+        $this->each(function (SplFileInfo $file, SplFileInfo $otherPath) use (&$differences) {
             $comparison = new CompareFile($file->getPathname(), $otherPath->getPathname());
             if (! $comparison->hasDifferences()) {
                 return null;
diff --git a/tests/CompareDirectoryTest.php b/tests/CompareDirectoryTest.php
index 91fdf2b..2ee522b 100644
--- a/tests/CompareDirectoryTest.php
+++ b/tests/CompareDirectoryTest.php
@@ -5,6 +5,8 @@
 use PHPUnit\Framework\TestCase;
 use SupportPal\LanguageTools\IO\Compare\CompareDirectory;
 
+use function count;
+
 class CompareDirectoryTest extends TestCase
 {
     public function testSuccess(): void
@@ -20,6 +22,6 @@ public function testFail(): void
         $base = __DIR__.'/__fixtures__/fail';
         $comparison = new CompareDirectory($base.'/en', $base.'/es');
 
-        $this->assertGreaterThan(0, $comparison->diff());
+        $this->assertGreaterThan(0, count($comparison->diff()));
     }
 }