diff --git a/clang/lib/Analysis/FlowSensitive/Transfer.cpp b/clang/lib/Analysis/FlowSensitive/Transfer.cpp
index 513f22d8aa0f9..fe13e919bddcd 100644
--- a/clang/lib/Analysis/FlowSensitive/Transfer.cpp
+++ b/clang/lib/Analysis/FlowSensitive/Transfer.cpp
@@ -664,6 +664,7 @@ class TransferVisitor : public ConstStmtVisitor<TransferVisitor> {
     QualType Type = S->getType();
 
     if (Type->isUnionType()) {
+      // FIXME: Initialize unions properly.
       if (auto *Val = Env.createValue(Type))
         Env.setValue(*S, *Val);
       return;