diff --git a/lib/models/LtiData.php b/lib/models/LtiData.php
index fd2014676bb144fb3cf66c181589b6a3863bceaf..2f0a08d41a154fe505bd816f38084de5f9f3916a 100644
--- a/lib/models/LtiData.php
+++ b/lib/models/LtiData.php
@@ -111,7 +111,7 @@ class LtiData extends SimpleORMap
             return $this->tool->oauth_signature_method;
         }
 
-        return $this->options['oauth_signature_method'];
+        return $this->options['oauth_signature_method'] ?? 'sha1';
     }
 
     /**