diff --git a/clientapi/routing/routing.go b/clientapi/routing/routing.go
index ced75303e..4e7a05b82 100644
--- a/clientapi/routing/routing.go
+++ b/clientapi/routing/routing.go
@@ -94,6 +94,7 @@ func Setup(
 	unstableFeatures := map[string]bool{
 		"org.matrix.e2e_cross_signing": true,
 		"org.matrix.msc2285.stable":    true,
+		"org.matrix.msc3916":           true,
 	}
 	for _, msc := range cfg.MSCs.MSCs {
 		unstableFeatures["org.matrix."+msc] = true
diff --git a/internal/httputil/httpapi.go b/internal/httputil/httpapi.go
index 26b2f4d73..921c12a0e 100644
--- a/internal/httputil/httpapi.go
+++ b/internal/httputil/httpapi.go
@@ -226,7 +226,7 @@ func MakeHTMLAPI(metricsName string, userAPI userapi.QueryAcccessTokenAPI, enabl
 			if jsonErr != nil {
 				logger.Debugf("VerifyUserFromRequest %s -> HTTP %d", req.RemoteAddr, jsonErr.Code)
 				w.WriteHeader(jsonErr.Code)
-				if err := json.NewEncoder(w).Encode(jsonErr); err != nil {
+				if err := json.NewEncoder(w).Encode(jsonErr.JSON); err != nil {
 					logger.WithError(err).Error("failed to encode JSON response")
 				}
 				return