diff --git a/src/HttpBaseTest.php b/src/HttpBaseTest.php
index 72bcf62..2c4a993 100644
--- a/src/HttpBaseTest.php
+++ b/src/HttpBaseTest.php
@@ -270,6 +270,10 @@ protected function assertRequest(
 
             $name = strtoupper(str_replace('-', '_', 'http-'.$name));
 
+            if ($method === 'TRACE' && $name === 'HTTP_CONTENT_LENGTH' && !isset($request['SERVER'][$name])) {
+                continue;
+            }
+
             $this->assertArrayHasKey($name, $request['SERVER']);
             $this->assertSame($value, $request['SERVER'][$name], "Failed asserting value for {$name}.");
         }