diff --git a/windows/winhandl.c b/windows/winhandl.c
index 7a3cce35..222e5b93 100644
--- a/windows/winhandl.c
+++ b/windows/winhandl.c
@@ -102,6 +102,7 @@ static DWORD WINAPI handle_input_threadfunc(void *param)
     struct handle_input *ctx = (struct handle_input *) param;
     OVERLAPPED ovl, *povl;
     HANDLE oev;
+    int readlen;
 
     if (ctx->flags & HANDLE_FLAG_OVERLAPPED) {
 	povl = &ovl;
@@ -110,12 +111,17 @@ static DWORD WINAPI handle_input_threadfunc(void *param)
 	povl = NULL;
     }
 
+    if (ctx->flags & HANDLE_FLAG_UNITBUFFER)
+	readlen = 1;
+    else
+	readlen = sizeof(ctx->buffer);
+
     while (1) {
 	if (povl) {
 	    memset(povl, 0, sizeof(OVERLAPPED));
 	    povl->hEvent = oev;
 	}
-	ctx->readret = ReadFile(ctx->h, ctx->buffer, sizeof(ctx->buffer),
+	ctx->readret = ReadFile(ctx->h, ctx->buffer, readlen,
 				&ctx->len, povl);
 	if (povl && !ctx->readret && GetLastError() == ERROR_IO_PENDING) {
 	    WaitForSingleObject(povl->hEvent, INFINITE);
diff --git a/windows/winser.c b/windows/winser.c
index f50eea13..21ff9a24 100644
--- a/windows/winser.c
+++ b/windows/winser.c
@@ -241,7 +241,8 @@ static const char *serial_init(void *frontend_handle, void **backend_handle,
 				    HANDLE_FLAG_OVERLAPPED);
     serial->in = handle_input_new(serport, serial_gotdata, serial,
 				  HANDLE_FLAG_OVERLAPPED |
-				  HANDLE_FLAG_IGNOREEOF);
+				  HANDLE_FLAG_IGNOREEOF |
+				  HANDLE_FLAG_UNITBUFFER);
 
     *realhost = dupstr(cfg->serline);
 
diff --git a/windows/winstuff.h b/windows/winstuff.h
index 9244c75c..08ebb043 100644
--- a/windows/winstuff.h
+++ b/windows/winstuff.h
@@ -410,6 +410,7 @@ void init_ucs(Config *, struct unicode_data *);
  */
 #define HANDLE_FLAG_OVERLAPPED 1
 #define HANDLE_FLAG_IGNOREEOF 2
+#define HANDLE_FLAG_UNITBUFFER 3
 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);