diff --git a/src/libsystemd/sd-bus/bus-message.c b/src/libsystemd/sd-bus/bus-message.c
index f966dda229..b8cd5e6417 100644
--- a/src/libsystemd/sd-bus/bus-message.c
+++ b/src/libsystemd/sd-bus/bus-message.c
@@ -3189,6 +3189,8 @@ static int container_next_item(sd_bus_message *m, struct bus_container *c, size_
                 int sz;
 
                 sz = bus_gvariant_get_size(c->signature);
+                if (sz == 0)
+                        return -EBADMSG;
                 if (sz < 0) {
                         int alignment;