--- common.inc	2006-08-26 15:19:09.000000000 +0100
+++ common.inc.new	2006-08-29 17:24:33.000000000 +0100
@@ -399,9 +399,11 @@
     // We don't add the port to prevent from breaking rewrite rules checking
     // the host that do not take into account the port number.
     'Host' => "Host: $host",
-    'User-Agent' => 'User-Agent: Drupal (+http://drupal.org/)',
-    'Content-Length' => 'Content-Length: '. strlen($data)
-  );
+    'User-Agent' => 'User-Agent: Drupal (+http://drupal.org/)'
+	);
+  if (strlen($data) > 0) {
+    $defaults['Content-Length'] = 'Content-Length: '. strlen($data);
+  }
 
   foreach ($headers as $header => $value) {
     $defaults[$header] = $header .': '. $value;