diff --git a/phpBB/config/default/container/services_storage.yml b/phpBB/config/default/container/services_storage.yml
index 4e37ffbce0..32b74687c9 100644
--- a/phpBB/config/default/container/services_storage.yml
+++ b/phpBB/config/default/container/services_storage.yml
@@ -39,6 +39,7 @@ services:
         arguments:
             - '@filesystem'
             - '@upload_imagesize'
+            - '@mimetype.guesser'
             - '%core.root_path%'
         tags:
             - { name: storage.adapter }
diff --git a/phpBB/phpbb/storage/adapter/local.php b/phpBB/phpbb/storage/adapter/local.php
index 4004669e44..1ef2516f4f 100644
--- a/phpBB/phpbb/storage/adapter/local.php
+++ b/phpBB/phpbb/storage/adapter/local.php
@@ -18,6 +18,7 @@ use phpbb\storage\exception\exception;
 use phpbb\filesystem\exception\filesystem_exception;
 use phpbb\filesystem\filesystem;
 use phpbb\filesystem\helper as filesystem_helper;
+use phpbb\mimetype\guesser;
 use FastImageSize\FastImageSize;
 
 /**
@@ -33,12 +34,19 @@ class local implements adapter_interface, stream_interface
 	protected $filesystem;
 
 	/**
-	 * Filesystem component
+	 * FastImageSize
 	 *
 	 * @var \FastImageSize\FastImageSize
 	 */
 	protected $imagesize;
 
+	/**
+	 * Mimetype Guesser component
+	 *
+	 * @var \phpbb\mimetype\guesser
+	 */
+	protected $mimetype_guesser;
+
 	/**
 	 * @var string path
 	 */
@@ -52,10 +60,11 @@ class local implements adapter_interface, stream_interface
 	/**
 	 * Constructor
 	 */
-	public function __construct(filesystem $filesystem, FastImageSize $imagesize, $phpbb_root_path)
+	public function __construct(filesystem $filesystem, FastImageSize $imagesize, guesser $mimetype_guesser, $phpbb_root_path)
 	{
 		$this->filesystem = $filesystem;
 		$this->imagesize = $imagesize;
+		$this->mimetype_guesser = $mimetype_guesser;
 		$this->phpbb_root_path = $phpbb_root_path;
 	}
 
@@ -275,17 +284,7 @@ class local implements adapter_interface, stream_interface
 	 */
 	public function file_mimetype($path)
 	{
-		if (class_exists('finfo'))
-		{
-			$finfo = new \finfo(FILEINFO_MIME_TYPE);
-			$mimetype = $finfo->file($this->root_path . $path);
-		}
-		else
-		{
-			$mimetype = mime_content_type($this->root_path . $path);
-		}
-
-		return ['mimetype' => $mimetype];
+		return ['mimetype' => $this->mimetype_guesser->guess($this->root_path . $path)];
 	}
 
 	/**
diff --git a/tests/avatar/manager_test.php b/tests/avatar/manager_test.php
index d0ff67b6e1..c276281fee 100644
--- a/tests/avatar/manager_test.php
+++ b/tests/avatar/manager_test.php
@@ -36,7 +36,7 @@ class phpbb_avatar_manager_test extends \phpbb_database_test_case
 			->will($this->returnArgument(0));
 
 		$filesystem = new \phpbb\filesystem\filesystem();
-		$adapter = new \phpbb\storage\adapter\local($filesystem, new \FastImageSize\FastImageSize(), $phpbb_root_path);
+		$adapter = new \phpbb\storage\adapter\local($filesystem, new \FastImageSize\FastImageSize(), new \phpbb\mimetype\guesser(array(new \phpbb\mimetype\extension_guesser)), $phpbb_root_path);
 		$adapter->configure(['path' => 'images/avatars/upload']);
 		$adapter_factory_mock = $this->createMock('\phpbb\storage\adapter_factory');
 		$adapter_factory_mock->expects($this->any())
diff --git a/tests/storage/adapter/local_test.php b/tests/storage/adapter/local_test.php
index 09b4568cd6..b478ce4009 100644
--- a/tests/storage/adapter/local_test.php
+++ b/tests/storage/adapter/local_test.php
@@ -24,7 +24,7 @@
 		$filesystem = new \phpbb\filesystem\filesystem();
 		$phpbb_root_path = getcwd() . DIRECTORY_SEPARATOR;
 
-		$this->adapter = new \phpbb\storage\adapter\local($filesystem, new \FastImageSize\FastImageSize(), $phpbb_root_path);
+		$this->adapter = new \phpbb\storage\adapter\local($filesystem, new \FastImageSize\FastImageSize(), new \phpbb\mimetype\guesser(array(new \phpbb\mimetype\extension_guesser)), $phpbb_root_path);
 		$this->adapter->configure(['path' => 'test_path']);
 
 		$this->path = $phpbb_root_path . 'test_path/';