diff --git a/src/accordproject/runtime.cto b/src/accordproject/runtime.cto
index a2926ed..bff3b74 100644
--- a/src/accordproject/runtime.cto
+++ b/src/accordproject/runtime.cto
@@ -37,7 +37,7 @@ abstract concept ErrorResponse {
 }
 
 /* An event that represents an obligation that needs to be fulfilled */
-abstract event Obligation {
+abstract event Obligation identified {
   /* A back reference to the governing contract that emitted this obligation */
   --> ContractData contractData