--- a/src/java.base/windows/native/libnio/ch/FileChannelImpl.c	Tue Aug 20 10:46:23 2019 +0200
+++ b/src/java.base/windows/native/libnio/ch/FileChannelImpl.c	Tue Aug 20 10:11:53 2019 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -60,7 +60,7 @@
 
 JNIEXPORT jlong JNICALL
 Java_sun_nio_ch_FileChannelImpl_map0(JNIEnv *env, jobject this,
-                               jint prot, jlong off, jlong len)
+                                     jint prot, jlong off, jlong len, jboolean map_sync)
 {
     void *mapAddress = 0;
     jint lowOffset = (jint)off;
@@ -87,6 +87,11 @@
         mapAccess = FILE_MAP_COPY;
     }
 
+    if (map_sync) {
+        JNU_ThrowInternalError(env, "should never call map on platform where MAP_SYNC is unimplemented");
+        return IOS_THROWN;
+    }
+
     mapping = CreateFileMapping(
         fileHandle,      /* Handle of file */
         NULL,            /* Not inheritable */