diff --git a/app/Helper/UserHelper.php b/app/Helper/UserHelper.php
index 5c466df33..ae3efe1dc 100644
--- a/app/Helper/UserHelper.php
+++ b/app/Helper/UserHelper.php
@@ -36,10 +36,10 @@ class UserHelper extends Base
         $initials = '';
 
         foreach (explode(' ', $name, 2) as $string) {
-            $initials .= mb_substr($string, 0, 1);
+            $initials .= mb_substr($string, 0, 1, 'UTF-8');
         }
 
-        return mb_strtoupper($initials);
+        return mb_strtoupper($initials, 'UTF-8');
     }
 
     /**
@@ -174,7 +174,7 @@ class UserHelper extends Base
         if (isset($task['creator_id']) && $task['creator_id'] == $this->userSession->getId()) {
             return true;
         }
-        
+
         if ($this->userSession->isAdmin() || $this->getProjectUserRole($task['project_id']) === Role::PROJECT_MANAGER) {
             return true;
         }
diff --git a/tests/units/Helper/UserHelperTest.php b/tests/units/Helper/UserHelperTest.php
index c149e6639..10bbc58e7 100644
--- a/tests/units/Helper/UserHelperTest.php
+++ b/tests/units/Helper/UserHelperTest.php
@@ -20,6 +20,7 @@ class UserHelperTest extends Base
         $this->assertEquals('CN', $helper->getInitials('chuck norris'));
         $this->assertEquals('CN', $helper->getInitials('chuck norris #2'));
         $this->assertEquals('A', $helper->getInitials('admin'));
+        $this->assertEquals('Ü君', $helper->getInitials('Ü 君が代'));
     }
 
     public function testGetRoleName()
diff --git a/tests/units/User/Avatar/LetterAvatarProviderTest.php b/tests/units/User/Avatar/LetterAvatarProviderTest.php
index 39e51c98e..0eb3ef8e8 100644
--- a/tests/units/User/Avatar/LetterAvatarProviderTest.php
+++ b/tests/units/User/Avatar/LetterAvatarProviderTest.php
@@ -34,4 +34,12 @@ class LetterAvatarProviderTest extends Base
         $expected = '<div class="avatar-letter" style="background-color: rgb(134, 45, 132)" title="admin">A</div>';
         $this->assertEquals($expected, $provider->render($user, 48));
     }
+
+    public function testRenderWithUTF8()
+    {
+        $provider = new LetterAvatarProvider($this->container);
+        $user = array('id' => 123, 'name' => 'ü', 'username' => 'admin', 'email' => '');
+        $expected = '<div class="avatar-letter" style="background-color: rgb(62, 147, 31)" title="ü">Ü</div>';
+        $this->assertEquals($expected, $provider->render($user, 48));
+    }
 }