diff --git a/lib/SimpleSAML/IdP.php b/lib/SimpleSAML/IdP.php
index 6110df9c7abad24956ff47c8e434bf31609744fb..8e0d9511361cac9fd9fe6563597551fbb49c634c 100644
--- a/lib/SimpleSAML/IdP.php
+++ b/lib/SimpleSAML/IdP.php
@@ -485,7 +485,7 @@ class IdP
         if ($assocId !== null) {
             $this->terminateAssociation($assocId);
             $session = Session::getSessionFromRequest();
-            $session->deleteData('core:idp-ssotime', $this->id.':'.$state['saml:SPEntityId']);
+            $session->deleteData('core:idp-ssotime', $this->id.';'.$state['saml:SPEntityId']);
         }
 
         // terminate the local session