diff --git a/core/src/main/kotlin/net/corda/flows/NotaryFlow.kt b/core/src/main/kotlin/net/corda/flows/NotaryFlow.kt
index ec0f642dda..52e6468215 100644
--- a/core/src/main/kotlin/net/corda/flows/NotaryFlow.kt
+++ b/core/src/main/kotlin/net/corda/flows/NotaryFlow.kt
@@ -101,6 +101,7 @@ object NotaryFlow {
 
             val result = try {
                 validateTimestamp(wtx)
+                // TODO:  Move the duplicate input detection to `TransactionType.verify()`.
                 detectDuplicateInputs(wtx)
                 beforeCommit(stx)
                 commitInputStates(wtx)