diff --git a/bn-tests.rkt b/bn-tests.rkt
new file mode 100644
index 0000000..f7867db
--- /dev/null
+++ b/bn-tests.rkt
@@ -0,0 +1,7 @@
+#lang typed/racket
+
+;;; Tests for dds/bn.
+
+(require typed/rackunit "bn.rkt")
+
+(check-equal? (+ 1 2 3) 6)