Add disclaimer to README
diff --git a/README.md b/README.md
index d6cfa18..e12ded8 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,12 @@
 * Converting a list of bytes into a base64-encoded string.
 * Converting a Base 64 encoded String into list of bytes.
 
+## Disclaimer
+
+Support for this library is given as _best effort_.
+
+This library has not been reviewed or vetted by security professionals.
+
 ## Features and bugs
 
 Please file feature requests and bugs at the [issue tracker][tracker].