diff --git a/include/Contact.php b/include/Contact.php
index f7b32d6e6..956e8e291 100644
--- a/include/Contact.php
+++ b/include/Contact.php
@@ -1,5 +1,6 @@
 <?php
 
+require_once('include/Probe.php');
 
 // Included here for completeness, but this is a very dangerous operation.
 // It is the caller's responsibility to confirm the requestor's intent and