diff --git a/src/Network/WebSockets/Handshake/Http.hs b/src/Network/WebSockets/Handshake/Http.hs
--- a/src/Network/WebSockets/Handshake/Http.hs
+++ b/src/Network/WebSockets/Handshake/Http.hs
@@ -120,7 +120,7 @@
 -- | An upgrade response
 response101 :: Headers -> B.ByteString -> Response
 response101 headers body = Response 101 "WebSocket Protocol Handshake"
-    (("Upgrade", "WebSocket") : ("Connection", "Upgrade") : headers)
+    (("Upgrade", "websocket") : ("Connection", "Upgrade") : headers)
     body
 
 -- | Bad request
diff --git a/websockets.cabal b/websockets.cabal
--- a/websockets.cabal
+++ b/websockets.cabal
@@ -1,5 +1,5 @@
 Name:    websockets
-Version: 0.6.0.2
+Version: 0.6.0.3
 
 Synopsis:
   A sensible and clean way to write WebSocket-capable servers in Haskell.