diff --git a/src/main.c b/src/main.c
index 1a1d15ed4b..d0c762081c 100644
--- a/src/main.c
+++ b/src/main.c
@@ -230,7 +230,7 @@ static int ftruncate (int fd, curl_off_t where)
   if (_lseeki64(fd, where, SEEK_SET) < 0)
      return -1;
 
-  if (_write(fd, curr, SEEK_SET) < 0)
+  if (_write(fd, 0, 0) < 0)
      rc = -1;
   _lseeki64(fd, curr, SEEK_SET);
   return rc;