diff --git a/mnet/lib.php b/mnet/lib.php
index e878964b72c..3937b4491f3 100644
--- a/mnet/lib.php
+++ b/mnet/lib.php
@@ -259,7 +259,7 @@ function mnet_encrypt_message($message, $remote_certificate) {
     // Generate a key resource from the remote_certificate text string
     $publickey = openssl_get_publickey($remote_certificate);
 
-    if ( gettype($publickey) != 'resource' ) {
+    if ($publickey === false) {
         // Remote certificate is faulty.
         return false;
     }