core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php b/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php
index 606e378..2edcc74 100644
--- a/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php
@@ -28,7 +28,7 @@ public function getContext($query_arg = NULL) {
       return $this->requestStack->getCurrentRequest()->getQueryString();
     }
     else {
-      return $this->requestStack->getCurrentRequest()->query->get($query_arg);
+      return $this->requestStack->getCurrentRequest()->query->has($query_arg) ? '?valueless?' : $this->requestStack->getCurrentRequest()->query->get($query_arg);
     }
   }