diff --git a/actions/twitapidirect_messages.php b/actions/twitapidirect_messages.php
index ed2d5c5d1c..a04ae5fa76 100644
--- a/actions/twitapidirect_messages.php
+++ b/actions/twitapidirect_messages.php
@@ -104,7 +104,8 @@ class Twitapidirect_messagesAction extends TwitterapiAction {
 		$user = $apidata['user'];
 		$source = $this->trimmed('source');  // Not supported by Twitter.
 
-		if (!$source) {
+        $reserved_sources = array('web', 'omb', 'mail', 'xmpp', 'api');
+		if (!$source || in_array($source, $reserved_sources)) {
 			$source = 'api';
 		}
 
diff --git a/actions/twitapistatuses.php b/actions/twitapistatuses.php
index 1b095079aa..6d6d5266ff 100644
--- a/actions/twitapistatuses.php
+++ b/actions/twitapistatuses.php
@@ -239,8 +239,8 @@ class TwitapistatusesAction extends TwitterapiAction {
 		$status = $this->trimmed('status');
 		$source = $this->trimmed('source');
 		$in_reply_to_status_id = intval($this->trimmed('in_reply_to_status_id'));
-
-		if (!$source) {
+        $reserved_sources = array('web', 'omb', 'mail', 'xmpp', 'api');
+		if (!$source || in_array($source, $reserved_sources)) {
 			$source = 'api';
 		}