--- a/src/os/win32/ngx_sendv.c
+++ b/src/os/win32/ngx_sendv.c
@@ -6,29 +6,39 @@
 #include <ngx_log.h>
 #include <ngx_sendv.h>
 
+#include <ngx_string.h>
+
 ssize_t ngx_sendv(ngx_connection_t *c, ngx_iovec_t *iovec, int n)
 {
-     int        rc;
-     size_t     sent;
-     ngx_err_t  err;
+    int         rc;
+    size_t      sent;
+    ngx_err_t   err;
 
-     ngx_log_debug(c->log, "WSASend() start");
+#if 0
+    /* STUB: WSABUF must be 4-byte aligned. Undocumented WSAEINVAL error */
+    ngx_iovec_t iov[10];
+    ngx_memcpy(iov, iovec, n * sizeof(ngx_iovec_t));
+#endif
 
-     rc = WSASend(c->fd, iovec, n, &sent, 0, NULL, NULL);
+    sent = 0;
 
-     ngx_log_debug(c->log, "WSASend() done");
+    ngx_log_debug(c->log, "WSASend: %d, %d, %08x" _ c->fd _ n _ iovec);
+
+    rc = WSASend(c->fd, iovec, n, &sent, 0, NULL, NULL);
 
-     if (rc == -1) {
-         err = ngx_socket_errno;
+    ngx_log_debug(c->log, "WSASend() done");
+
+    if (rc == SOCKET_ERROR) {
+        err = ngx_socket_errno;
 
-         if (err == NGX_EAGAIN) {
-             ngx_log_error(NGX_LOG_INFO, c->log, err, "WSASend() eagain");
-             return NGX_AGAIN;
-         }
+        if (err == NGX_EAGAIN) {
+            ngx_log_error(NGX_LOG_INFO, c->log, err, "WSASend() eagain");
+            return NGX_AGAIN;
+        }
 
-         ngx_log_error(NGX_LOG_ERR, c->log, err, "WSASend() failed");
-         return NGX_ERROR;
-     }
+        ngx_log_error(NGX_LOG_ERR, c->log, err, "WSASend() failed");
+        return NGX_ERROR;
+    }
 
-     return sent;
+    return sent;
 }