diff --git a/wire.c b/wire.c
index f8ac6c4..1b533bf 100644
--- a/wire.c
+++ b/wire.c
@@ -128,6 +128,11 @@ int wire_parse_message(wire_context_t *c, wire_message_t *msg)
 {
     // SPEC: https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-messages
     msg->endianness = *(uint8_t*)TRYPTR(wire_get_u8(c));
+    if (msg->endianness == 'B') {
+        // we only support little endian
+        return -1;
+    }
+
     msg->type = *(uint8_t*)TRYPTR(wire_get_u8(c));
     msg->flags = *(uint8_t*)TRYPTR(wire_get_u8(c));
     msg->protocol_version = *(uint8_t*)TRYPTR(wire_get_u8(c));