diff --git a/app/messages/messages_thread.php b/app/messages/messages_thread.php
index 0d54e34140..488fd406a6 100644
--- a/app/messages/messages_thread.php
+++ b/app/messages/messages_thread.php
@@ -41,7 +41,7 @@
 
 //get number of messages to load
 	$number = preg_replace('{[\D]}', '', $_GET['number']);
-	$contact_uuid = $_GET['contact_uuid'];
+	$contact_uuid = (is_uuid($_GET['contact_uuid'])) ? $_GET['contact_uuid'] : null;
 
 //set refresh flag
 	$refresh = $_GET['refresh'] == 'true' ? true : false;
@@ -335,4 +335,4 @@
 		}
 	}
 
-?>
\ No newline at end of file
+?>