diff --git a/errsock.c b/errsock.c
index 9ab7c3db..e691dec2 100644
--- a/errsock.c
+++ b/errsock.c
@@ -50,7 +50,6 @@ static const SocketVtable ErrorSocket_sockvt = {
     NULL /* write */,
     NULL /* write_oob */,
     NULL /* write_eof */,
-    NULL /* flush */,
     NULL /* set_frozen */,
     sk_error_socket_error,
     sk_error_peer_info,
diff --git a/network.h b/network.h
index 689b4c5f..b86c054a 100644
--- a/network.h
+++ b/network.h
@@ -31,7 +31,6 @@ struct SocketVtable {
     size_t (*write) (Socket *s, const void *data, size_t len);
     size_t (*write_oob) (Socket *s, const void *data, size_t len);
     void (*write_eof) (Socket *s);
-    void (*flush) (Socket *s);
     void (*set_frozen) (Socket *s, bool is_frozen);
     /* ignored by tcp, but vital for ssl */
     const char *(*socket_error) (Socket *s);
@@ -158,8 +157,6 @@ static inline size_t sk_write_oob(Socket *s, const void *data, size_t len)
 { return s->vt->write_oob(s, data, len); }
 static inline void sk_write_eof(Socket *s)
 { s->vt->write_eof(s); }
-static inline void sk_flush(Socket *s)
-{ s->vt->flush(s); }
 
 static inline void plug_log(
     Plug *p, int type, SockAddr *addr, int port, const char *msg, int code)
diff --git a/proxy.c b/proxy.c
index e9ab244d..c3bea773 100644
--- a/proxy.c
+++ b/proxy.c
@@ -57,11 +57,6 @@ void proxy_activate (ProxySocket *p)
     if (output_after < output_before)
         plug_sent(p->plug, output_after);
 
-    /* if we were asked to flush the output during
-     * the proxy negotiation process, do so now.
-     */
-    if (p->pending_flush) sk_flush(p->sub_socket);
-
     /* if we have a pending EOF to send, send it */
     if (p->pending_eof) sk_write_eof(p->sub_socket);
 
@@ -128,17 +123,6 @@ static void sk_proxy_write_eof (Socket *s)
     sk_write_eof(ps->sub_socket);
 }
 
-static void sk_proxy_flush (Socket *s)
-{
-    ProxySocket *ps = container_of(s, ProxySocket, sock);
-
-    if (ps->state != PROXY_STATE_ACTIVE) {
-	ps->pending_flush = true;
-	return;
-    }
-    sk_flush(ps->sub_socket);
-}
-
 static void sk_proxy_set_frozen (Socket *s, bool is_frozen)
 {
     ProxySocket *ps = container_of(s, ProxySocket, sock);
@@ -393,7 +377,6 @@ static const struct SocketVtable ProxySocket_sockvt = {
     sk_proxy_write,
     sk_proxy_write_oob,
     sk_proxy_write_eof,
-    sk_proxy_flush,
     sk_proxy_set_frozen,
     sk_proxy_socket_error,
     NULL, /* peer_info */
@@ -437,7 +420,6 @@ Socket *new_connection(SockAddr *addr, const char *hostname,
 	ret->remote_port = port;
 
 	ret->error = NULL;
-	ret->pending_flush = false;
 	ret->pending_eof = false;
 	ret->freeze = false;
 
diff --git a/unix/uxfdsock.c b/unix/uxfdsock.c
index b6b43fa2..c7cab247 100644
--- a/unix/uxfdsock.c
+++ b/unix/uxfdsock.c
@@ -229,12 +229,6 @@ static void fdsocket_write_eof(Socket *s)
     fdsocket_try_send(fds);
 }
 
-static void fdsocket_flush(Socket *s)
-{
-    /* FdSocket *fds = container_of(s, FdSocket, sock); */
-    /* do nothing */
-}
-
 static void fdsocket_set_frozen(Socket *s, bool is_frozen)
 {
     FdSocket *fds = container_of(s, FdSocket, sock);
@@ -315,7 +309,6 @@ static const SocketVtable FdSocket_sockvt = {
     fdsocket_write,
     fdsocket_write_oob,
     fdsocket_write_eof,
-    fdsocket_flush,
     fdsocket_set_frozen,
     fdsocket_socket_error,
     NULL, /* peer_info */
diff --git a/unix/uxnet.c b/unix/uxnet.c
index ef452d3d..3b55772e 100644
--- a/unix/uxnet.c
+++ b/unix/uxnet.c
@@ -492,14 +492,6 @@ static Plug *sk_net_plug(Socket *sock, Plug *p)
     return ret;
 }
 
-static void sk_net_flush(Socket *s)
-{
-    /*
-     * We send data to the socket as soon as we can anyway,
-     * so we don't need to do anything here.  :-)
-     */
-}
-
 static void sk_net_close(Socket *s);
 static size_t sk_net_write(Socket *s, const void *data, size_t len);
 static size_t sk_net_write_oob(Socket *s, const void *data, size_t len);
@@ -514,7 +506,6 @@ static struct SocketVtable NetSocket_sockvt = {
     sk_net_write,
     sk_net_write_oob,
     sk_net_write_eof,
-    sk_net_flush,
     sk_net_set_frozen,
     sk_net_socket_error,
     sk_net_peer_info,
diff --git a/windows/winhsock.c b/windows/winhsock.c
index 7f2b4474..aa3b5a9f 100644
--- a/windows/winhsock.c
+++ b/windows/winhsock.c
@@ -156,12 +156,6 @@ static void sk_handle_write_eof(Socket *s)
     handle_write_eof(hs->send_h);
 }
 
-static void sk_handle_flush(Socket *s)
-{
-    /* HandleSocket *hs = container_of(s, HandleSocket, sock); */
-    /* do nothing */
-}
-
 static void handle_socket_unfreeze(void *hsv)
 {
     HandleSocket *hs = (HandleSocket *)hsv;
@@ -315,7 +309,6 @@ static const SocketVtable HandleSocket_sockvt = {
     sk_handle_write,
     sk_handle_write_oob,
     sk_handle_write_eof,
-    sk_handle_flush,
     sk_handle_set_frozen,
     sk_handle_socket_error,
     sk_handle_peer_info,
diff --git a/windows/winnet.c b/windows/winnet.c
index ae5b11f6..535e37b9 100644
--- a/windows/winnet.c
+++ b/windows/winnet.c
@@ -823,14 +823,6 @@ static Plug *sk_net_plug(Socket *sock, Plug *p)
     return ret;
 }
 
-static void sk_net_flush(Socket *s)
-{
-    /*
-     * We send data to the socket as soon as we can anyway,
-     * so we don't need to do anything here.  :-)
-     */
-}
-
 static void sk_net_close(Socket *s);
 static size_t sk_net_write(Socket *s, const void *data, size_t len);
 static size_t sk_net_write_oob(Socket *s, const void *data, size_t len);
@@ -845,7 +837,6 @@ static const SocketVtable NetSocket_sockvt = {
     sk_net_write,
     sk_net_write_oob,
     sk_net_write_eof,
-    sk_net_flush,
     sk_net_set_frozen,
     sk_net_socket_error,
     sk_net_peer_info,
diff --git a/windows/winnps.c b/windows/winnps.c
index fa1d804b..5c201641 100644
--- a/windows/winnps.c
+++ b/windows/winnps.c
@@ -192,7 +192,7 @@ static void named_pipe_connect_callback(void *vps)
 
 /*
  * This socket type is only used for listening, so it should never
- * be asked to write or flush or set_frozen.
+ * be asked to write or set_frozen.
  */
 static const SocketVtable NamedPipeServerSocket_sockvt = {
     sk_namedpipeserver_plug,
@@ -200,7 +200,6 @@ static const SocketVtable NamedPipeServerSocket_sockvt = {
     NULL /* write */,
     NULL /* write_oob */,
     NULL /* write_eof */,
-    NULL /* flush */,
     NULL /* set_frozen */,
     sk_namedpipeserver_socket_error,
     sk_namedpipeserver_peer_info,