diff --git a/docs/hazmat/primitives/key-derivation-functions.rst b/docs/hazmat/primitives/key-derivation-functions.rst
index da47ccd..d8a0e24 100644
--- a/docs/hazmat/primitives/key-derivation-functions.rst
+++ b/docs/hazmat/primitives/key-derivation-functions.rst
@@ -128,7 +128,10 @@
 
     `HKDF`_ (HMAC-based Extract-and-Expand Key Derivation Function) is suitable
     for deriving keys of a fixed size used for other cryptographic operations.
-    **HKDF should not be used for password storage.**
+
+    .. warning::
+
+        HKDF should not be used for password storage.
 
     .. doctest::