diff -r febc37adfe80 -r 57d8566a2732 src/hotspot/os/windows/os_windows.cpp
--- a/src/hotspot/os/windows/os_windows.cpp	Sun Jan 13 17:33:26 2019 +0100
+++ b/src/hotspot/os/windows/os_windows.cpp	Sun Jan 13 16:54:01 2019 -0500
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -4539,7 +4539,7 @@
   return (jlong) ::_lseeki64(fd, offset, whence);
 }
 
-size_t os::read_at(int fd, void *buf, unsigned int nBytes, jlong offset) {
+ssize_t os::read_at(int fd, void *buf, unsigned int nBytes, jlong offset) {
   OVERLAPPED ov;
   DWORD nread;
   BOOL result;