diff --git a/packages/inter-protocol/src/vaultFactory/liquidateIncrementally.js b/packages/inter-protocol/src/vaultFactory/liquidateIncrementally.js
index 4ac2b6aecb2e..86c6b4fd5493 100644
--- a/packages/inter-protocol/src/vaultFactory/liquidateIncrementally.js
+++ b/packages/inter-protocol/src/vaultFactory/liquidateIncrementally.js
@@ -203,6 +203,7 @@ const start = async zcf => {
       // the generator, which this code drops. AFAICT, this code is
       // equivalent to `await null;`. It imposes a non-delayed turn boundary
       // and does nothing else.
+      // See https://github.com/Agoric/agoric-sdk/issues/6220
       await oncePerBlock();
 
       // Determine the max allowed tranche size