diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index 74853b2..b9f00f0 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -1212,7 +1212,7 @@ function drupal_send_headers($default_headers = array(), $only_default = FALSE)
       header($_SERVER['SERVER_PROTOCOL'] . ' ' . $value);
     }
     // Skip headers that have been unset.
-    elseif ($value) {
+    elseif ($value !== FALSE) {
       header($header_names[$name_lower] . ': ' . $value);
     }
   }