diff --git a/src/Lean/Elab/Do.lean b/src/Lean/Elab/Do.lean
index fc95262c65..35525b7344 100644
--- a/src/Lean/Elab/Do.lean
+++ b/src/Lean/Elab/Do.lean
@@ -934,6 +934,8 @@ unit ← `(PUnit.unit);
 let unit := unit.copyInfo ref;
 pure $ mkReturn ref unit
 
+-- TODO: we must expand macros occurring in patterns before invoking getPatternVars
+
 partial def doSeqToCode : List Syntax → M CodeBlock
 | [] => do ctx ← read; mkReturnUnit ctx.ref
 | doElem::doElems => withRef doElem do