diff --git a/core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php b/core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php
index 7dd55bf..71db8e6 100644
--- a/core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php
@@ -33,6 +33,8 @@ public function getContext($header = NULL) {
         if ($result) {
           $result .= '&';
         }
+        // Sort values to minimize cache variations.
+        sort($value);
         $result .= $name . '=' . implode(',', $value);
       }
       return $result;
diff --git a/core/tests/Drupal/Tests/Core/Cache/Context/HeadersCacheContextTest.php b/core/tests/Drupal/Tests/Core/Cache/Context/HeadersCacheContextTest.php
index b70f187..c1f4290 100644
--- a/core/tests/Drupal/Tests/Core/Cache/Context/HeadersCacheContextTest.php
+++ b/core/tests/Drupal/Tests/Core/Cache/Context/HeadersCacheContextTest.php
@@ -45,7 +45,8 @@ public function providerTestGetContext() {
       [['llama' => 'rocks', 'alpaca' => '', 'panda' => 'drools', 'z' => '0'], 'chicken', ''],
       // Header value could be an array.
       [['z' => ['0', '1']], NULL, 'z=0,1'],
-      [['z' => ['0', '1'], 'a' => []], NULL, 'a=&z=0,1'],
+      // Values are sorted to minimize cache variations.
+      [['z' => ['1', '0'], 'a' => []], NULL, 'a=&z=0,1'],
     ];
   }