diff --git a/HeaderUtils.php b/HeaderUtils.php
index 3456edace..110896e17 100644
--- a/HeaderUtils.php
+++ b/HeaderUtils.php
@@ -286,7 +286,11 @@ private static function groupParts(array $matches, string $separators, bool $fir
         }
 
         foreach ($partMatches as $matches) {
-            $parts[] = '' === $separators ? self::unquote($matches[0][0]) : self::groupParts($matches, $separators, false);
+            if ('' === $separators && '' !== $unquoted = self::unquote($matches[0][0])) {
+                $parts[] = $unquoted;
+            } elseif ($groupedParts = self::groupParts($matches, $separators, false)) {
+                $parts[] = $groupedParts;
+            }
         }
 
         return $parts;
diff --git a/Tests/AcceptHeaderTest.php b/Tests/AcceptHeaderTest.php
index bf4582430..e972d714e 100644
--- a/Tests/AcceptHeaderTest.php
+++ b/Tests/AcceptHeaderTest.php
@@ -41,6 +41,8 @@ public static function provideFromStringData()
     {
         return [
             ['', []],
+            [';;;', []],
+            ['0', [new AcceptHeaderItem('0')]],
             ['gzip', [new AcceptHeaderItem('gzip')]],
             ['gzip,deflate,sdch', [new AcceptHeaderItem('gzip'), new AcceptHeaderItem('deflate'), new AcceptHeaderItem('sdch')]],
             ["gzip, deflate\t,sdch", [new AcceptHeaderItem('gzip'), new AcceptHeaderItem('deflate'), new AcceptHeaderItem('sdch')]],