diff --git a/src/brand.d.ts b/src/brand.d.ts
new file mode 100644
index 0000000..d46d3d9
--- /dev/null
+++ b/src/brand.d.ts
@@ -0,0 +1 @@
+type Brand<T, B> = T & { readonly __brand: B };
\ No newline at end of file