diff --git a/Hash2Pub/democlient.hs b/Hash2Pub/democlient.hs
index e59c1ed..f0bf03c 100644
--- a/Hash2Pub/democlient.hs
+++ b/Hash2Pub/democlient.hs
@@ -13,6 +13,7 @@ import qualified Data.ByteString.UTF8 as BSU
 
 main = do
     sock <- socket AF_INET6 Datagram defaultProtocol
+    setSocketOption sock IPv6Only 1
     -- lookup destination to get a SockAddr
     let hints = defaultHints { addrFamily = AF_INET6, addrSocketType = Datagram}
     destAddr <- addrAddress . head <$> getAddrInfo (Just hints) (Just "::1") (Just "7331")
diff --git a/Hash2Pub/demoserver.hs b/Hash2Pub/demoserver.hs
index 99562d3..a9eda95 100644
--- a/Hash2Pub/demoserver.hs
+++ b/Hash2Pub/demoserver.hs
@@ -14,6 +14,7 @@ import qualified Data.ByteString as BS
 
 main = do
     sock <- socket AF_INET6 Datagram defaultProtocol
+    setSocketOption sock IPv6Only 1
     -- lookup destination to get a SockAddr
     let hints = defaultHints { addrFamily = AF_INET6, addrSocketType = Datagram}
     serverAddr <- addrAddress . head <$> getAddrInfo (Just hints) (Just "::1") (Just "7331")