diff --git a/README.md b/README.md
index 4713705..5e64921 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,8 @@
 
 Hashing algorithms with a straight-forward API and no dependencies.
 
+Nightly toolchain required.
+
 Currently implements:
 
 -   MD2, MD4, and MD5