diff --git a/windows/winhandl.c b/windows/winhandl.c
index e45eb9b5..fc641812 100644
--- a/windows/winhandl.c
+++ b/windows/winhandl.c
@@ -74,6 +74,11 @@ struct handle_input {
     int busy;			       /* operation currently in progress? */
     void *privdata;		       /* for client to remember who they are */
 
+    /*
+     * Data set at initialisation and then read-only.
+     */
+    int flags;
+
     /*
      * Data set by the input thread before signalling ev_to_main,
      * and read by the main thread after receiving that signal.
@@ -95,13 +100,28 @@ struct handle_input {
 static DWORD WINAPI handle_input_threadfunc(void *param)
 {
     struct handle_input *ctx = (struct handle_input *) param;
+    OVERLAPPED ovl, *povl;
+
+    if (ctx->flags & HANDLE_FLAG_OVERLAPPED)
+	povl = &ovl;
+    else
+	povl = NULL;
 
     while (1) {
+	if (povl)
+	    memset(povl, 0, sizeof(OVERLAPPED));
 	ctx->readret = ReadFile(ctx->h, ctx->buffer, sizeof(ctx->buffer),
-				&ctx->len, NULL);
+				&ctx->len, povl);
+	if (povl && !ctx->readret && GetLastError() == ERROR_IO_PENDING)
+	    ctx->readret = GetOverlappedResult(ctx->h, povl, &ctx->len, TRUE);
+
 	if (!ctx->readret)
 	    ctx->len = 0;
 
+	if (ctx->readret && ctx->len == 0 &&
+	    (ctx->flags & HANDLE_FLAG_IGNOREEOF))
+	    continue;
+
 	SetEvent(ctx->ev_to_main);
 
 	if (!ctx->len)
@@ -163,6 +183,11 @@ struct handle_output {
     int busy;			       /* operation currently in progress? */
     void *privdata;		       /* for client to remember who they are */
 
+    /*
+     * Data set at initialisation and then read-only.
+     */
+    int flags;
+
     /*
      * Data set by the main thread before signalling ev_from_main,
      * and read by the input thread after receiving that signal.
@@ -192,6 +217,12 @@ struct handle_output {
 static DWORD WINAPI handle_output_threadfunc(void *param)
 {
     struct handle_output *ctx = (struct handle_output *) param;
+    OVERLAPPED ovl, *povl;
+
+    if (ctx->flags & HANDLE_FLAG_OVERLAPPED)
+	povl = &ovl;
+    else
+	povl = NULL;
 
     while (1) {
 	WaitForSingleObject(ctx->ev_from_main, INFINITE);
@@ -199,8 +230,14 @@ static DWORD WINAPI handle_output_threadfunc(void *param)
 	    SetEvent(ctx->ev_to_main);
 	    break;
 	}
+	if (povl)
+	    memset(povl, 0, sizeof(OVERLAPPED));
 	ctx->writeret = WriteFile(ctx->h, ctx->buffer, ctx->len,
-				  &ctx->lenwritten, NULL);
+				  &ctx->lenwritten, povl);
+	if (povl && !ctx->writeret && GetLastError() == ERROR_IO_PENDING)
+	    ctx->writeret = GetOverlappedResult(ctx->h, povl,
+						&ctx->lenwritten, TRUE);
+
 	SetEvent(ctx->ev_to_main);
 	if (!ctx->writeret)
 	    break;
@@ -265,7 +302,7 @@ static int handle_find_evtomain(void *av, void *bv)
 }
 
 struct handle *handle_input_new(HANDLE handle, handle_inputfn_t gotdata,
-				void *privdata)
+				void *privdata, int flags)
 {
     struct handle *h = snew(struct handle);
 
@@ -278,6 +315,7 @@ struct handle *handle_input_new(HANDLE handle, handle_inputfn_t gotdata,
     h->u.i.moribund = FALSE;
     h->u.i.done = FALSE;
     h->u.i.privdata = privdata;
+    h->u.i.flags = flags;
 
     if (!handles_by_evtomain)
 	handles_by_evtomain = newtree234(handle_cmp_evtomain);
@@ -291,7 +329,7 @@ struct handle *handle_input_new(HANDLE handle, handle_inputfn_t gotdata,
 }
 
 struct handle *handle_output_new(HANDLE handle, handle_outputfn_t sentdata,
-				 void *privdata)
+				 void *privdata, int flags)
 {
     struct handle *h = snew(struct handle);
 
@@ -306,6 +344,7 @@ struct handle *handle_output_new(HANDLE handle, handle_outputfn_t sentdata,
     h->u.o.privdata = privdata;
     bufchain_init(&h->u.o.queued_data);
     h->u.o.sentdata = sentdata;
+    h->u.o.flags = flags;
 
     if (!handles_by_evtomain)
 	handles_by_evtomain = newtree234(handle_cmp_evtomain);
diff --git a/windows/winplink.c b/windows/winplink.c
index c85a6075..86ad00ff 100644
--- a/windows/winplink.c
+++ b/windows/winplink.c
@@ -578,8 +578,8 @@ int main(int argc, char **argv)
      * (The input one we leave until we're through the
      * authentication process.)
      */
-    stdout_handle = handle_output_new(outhandle, stdouterr_sent, NULL);
-    stderr_handle = handle_output_new(errhandle, stdouterr_sent, NULL);
+    stdout_handle = handle_output_new(outhandle, stdouterr_sent, NULL, 0);
+    stderr_handle = handle_output_new(errhandle, stdouterr_sent, NULL, 0);
 
     main_thread_id = GetCurrentThreadId();
 
@@ -594,7 +594,8 @@ int main(int argc, char **argv)
 	DWORD ticks;
 
 	if (!sending && back->sendok(backhandle)) {
-	    stdin_handle = handle_input_new(inhandle, stdin_gotdata, NULL);
+	    stdin_handle = handle_input_new(inhandle, stdin_gotdata, NULL,
+					    0);
 	    sending = TRUE;
 	}
 
diff --git a/windows/winproxy.c b/windows/winproxy.c
index 24e68f8a..5fecfc25 100644
--- a/windows/winproxy.c
+++ b/windows/winproxy.c
@@ -205,9 +205,10 @@ Socket platform_new_connection(SockAddr addr, char *hostname,
     ret->to_cmd_H = us_to_cmd;
     ret->from_cmd_H = us_from_cmd;
 
-    ret->from_cmd_h = handle_input_new(ret->from_cmd_H, localproxy_gotdata, ret);
-    ret->to_cmd_h = handle_output_new(ret->to_cmd_H,
-					localproxy_sentdata, ret);
+    ret->from_cmd_h = handle_input_new(ret->from_cmd_H, localproxy_gotdata,
+				       ret, 0);
+    ret->to_cmd_h = handle_output_new(ret->to_cmd_H, localproxy_sentdata,
+				      ret, 0);
 
     /* We are responsible for this and don't need it any more */
     sk_addr_free(addr);
diff --git a/windows/winstuff.h b/windows/winstuff.h
index afc8dde2..85c99f43 100644
--- a/windows/winstuff.h
+++ b/windows/winstuff.h
@@ -408,13 +408,15 @@ void init_ucs(Config *, struct unicode_data *);
 /*
  * Exports from winhandl.c.
  */
+#define HANDLE_FLAG_OVERLAPPED 1
+#define HANDLE_FLAG_IGNOREEOF 2
 struct handle;
 typedef int (*handle_inputfn_t)(struct handle *h, void *data, int len);
 typedef void (*handle_outputfn_t)(struct handle *h, int new_backlog);
 struct handle *handle_input_new(HANDLE handle, handle_inputfn_t gotdata,
-				void *privdata);
+				void *privdata, int flags);
 struct handle *handle_output_new(HANDLE handle, handle_outputfn_t sentdata,
-				 void *privdata);
+				 void *privdata, int flags);
 int handle_write(struct handle *h, const void *data, int len);
 HANDLE *handle_get_events(int *nevents);
 void handle_free(struct handle *h);