diff --git a/server/session.go b/server/session.go
index be601f8..a644a83 100644
--- a/server/session.go
+++ b/server/session.go
@@ -801,9 +801,15 @@ func (s *Session) hello(msg *ClientComMessage) {
 		}
 
 		tenantCode := strings.TrimSpace(msg.Hi.Tenant)
-		if tenantCode == "" || len(tenantCode) > 64 {
+		if tenantCode == "" {
+			// Clients that predate the tenant-aware protocol (stock Tinode
+			// webapp/mobile SDKs never send this field) fall back to the
+			// default tenant rather than being rejected. Clients that do
+			// send an explicit code are unaffected.
+			tenantCode = "default"
+		} else if len(tenantCode) > 64 {
 			s.queueOut(ErrMalformed(msg.Id, "", msg.Timestamp))
-			logs.Warn.Println("s.hello: tenant code is missing or invalid", s.sid)
+			logs.Warn.Println("s.hello: tenant code is invalid", s.sid)
 			return
 		}
 		if store.Tenants == nil {