diff --git a/spec.bs b/spec.bs
index 68582b661..7f7bd34a8 100644
--- a/spec.bs
+++ b/spec.bs
@@ -3373,15 +3373,15 @@ dictionary ReportWinBrowserSignals : ReportingBrowserSignals {
 
 <xmp class="idl">
 dictionary DirectFromSellerSignalsForBuyer {
-  any auctionSignals;
-  any perBuyerSignals;
+  any auctionSignals = null;
+  any perBuyerSignals = null;
 };
 </xmp>
 
 <xmp class="idl">
 dictionary DirectFromSellerSignalsForSeller {
-  any auctionSignals;
-  any sellerSignals;
+  any auctionSignals = null;
+  any sellerSignals = null;
 };
 </xmp>