diff --git a/lib/http/base.js b/lib/http/base.js
index f81d6a67..4797be1a 100644
--- a/lib/http/base.js
+++ b/lib/http/base.js
@@ -191,13 +191,13 @@ HTTPBase.prototype.basicAuth = function basicAuth(options) {
     assert(typeof user === 'string');
     assert(user.length <= 255, 'Username too long.');
     assert(util.isAscii(user), 'Username must be ASCII.');
-    user = digest.hash256(user);
+    user = digest.hash256(Buffer.from(user, 'ascii'));
   }
 
   assert(typeof pass === 'string');
   assert(pass.length <= 255, 'Password too long.');
   assert(util.isAscii(pass), 'Password must be ASCII.');
-  pass = digest.hash256(pass);
+  pass = digest.hash256(Buffer.from(pass, 'ascii'));
 
   if (!realm)
     realm = 'server';