diff --git a/test/number-only.test.sh b/test/number-only.test.sh
new file mode 100755
index 0000000..db0b6b4
--- /dev/null
+++ b/test/number-only.test.sh
@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+# Copyright (c) 2018 Joel Wallis Jucá <joelwallis@gmail.com>
+# ISC licensed
+
+@test "is a function" {
+  type numeric-only | grep function
+  [ "$status" -eq 0 ]
+
+  numeric-only
+  [ "$status" -eq 0 ]
+}