diff --git a/common/models/role.js b/common/models/role.js
index a86dfcff..406389d9 100644
--- a/common/models/role.js
+++ b/common/models/role.js
@@ -353,7 +353,11 @@ module.exports = function(Role) {
     context.principals.forEach(function(p) {
       // Check against the role mappings
       var principalType = p.type || undefined;
-      var principalId = p.id || undefined;
+      var principalId = p.id == null ? undefined : p.id;
+      
+      if(typeof principalId !== 'string' && principalId != null) {
+        principalId = principalId.toString();
+      }
 
       // Add the role itself
       if (principalType === RoleMapping.ROLE && principalId) {