From 9ec19dba6a6af4a18bf34abe5d9e4a6a703974ec Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Thu, 28 Apr 2022 11:15:43 +0100
Subject: [PATCH] Ensure signature map exists (fixes #2393)

---
 keyserver/internal/internal.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/keyserver/internal/internal.go b/keyserver/internal/internal.go
index e571c7e56..1677cf8e3 100644
--- a/keyserver/internal/internal.go
+++ b/keyserver/internal/internal.go
@@ -319,6 +319,9 @@ func (a *KeyInternalAPI) QueryKeys(ctx context.Context, req *api.QueryKeysReques
 	// JSON, add the signatures and marshal it again, for some reason?
 
 	for targetUserID, masterKey := range res.MasterKeys {
+		if masterKey.Signatures == nil {
+			masterKey.Signatures = map[string]map[gomatrixserverlib.KeyID]gomatrixserverlib.Base64Bytes{}
+		}
 		for targetKeyID := range masterKey.Keys {
 			sigMap, err := a.DB.CrossSigningSigsForTarget(ctx, req.UserID, targetUserID, targetKeyID)
 			if err != nil {