diff --git a/README.txt b/README.txt
index bf01e1b7c2..888dc92f1a 100644
--- a/README.txt
+++ b/README.txt
@@ -187,7 +187,23 @@ Using MSYS
 
   Because of some versioning issues, I had to run 'aclocal' prior to
   running the kconfig-frontends configure script.  See "Configuring NuttX"
-  below for futher information.
+  below for futher information.ifq
+
+  Unlike Cygwin, MSYS does not support symbolic links.  The 'ln -s' commnad
+  will, in fact, copy a directory!  This means that you Make.defs file will
+  have to include  defintion like:
+
+    ifeq ($(CONFIG_WINDOWS_MSYS),y)
+      DIRLINK = $(TOPDIR)/tools/copydir.sh
+      DIRUNLINK = $(TOPDIR)/tools/unlink.sh
+    endif
+
+  This will force the directory copies to work in a way that can be handled
+  by the NuttX build system.
+
+  To build the simulator under MSYS, you also need:
+
+    pacman -S zlib-devel
 
 Ubuntu Bash under Windows 10
 ----------------------------
diff --git a/arch/sim/src/.gitignore b/arch/sim/src/.gitignore
index e0d861c651..930fbdac82 100644
--- a/arch/sim/src/.gitignore
+++ b/arch/sim/src/.gitignore
@@ -1,6 +1,7 @@
 /Make.dep
 /.depend
 /Cygwin-names.dat
+/Msys-names.dat
 /Linux-names.dat
 /nuttx.rel
 /hostfs.h
diff --git a/arch/sim/src/Makefile b/arch/sim/src/Makefile
index 29c2943ff3..03f6d5e06c 100644
--- a/arch/sim/src/Makefile
+++ b/arch/sim/src/Makefile
@@ -256,6 +256,9 @@ GNU:
 GNU/Linux-names.dat: GNU nuttx-names.dat
 	$(Q) cp nuttx-names.dat $@
 
+Msys-names.dat: GNU nuttx-names.dat
+	$(Q) cp nuttx-names.dat $@
+
 Cygwin-names.dat: nuttx-names.dat
 ifeq ($())CONFIG_SIM_CYGWIN_DECORATED),y)
 	$(Q) cat $^ | sed -e "s/^/_/g" >$@
diff --git a/configs/sim/scripts/Make.defs b/configs/sim/scripts/Make.defs
index 68b1513a76..ab54cc566f 100644
--- a/configs/sim/scripts/Make.defs
+++ b/configs/sim/scripts/Make.defs
@@ -1,7 +1,8 @@
 ############################################################################
 # configs/sim/scripts/Make.defs
 #
-#   Copyright (C) 2008, 2011-2012, 2017 Gregory Nutt. All rights reserved.
+#   Copyright (C) 2008, 2011-2012, 2017-2018 Gregory Nutt. All rights
+#     reserved.
 #   Author: Gregory Nutt <gnutt@nuttx.org>
 #
 # Redistribution and use in source and binary forms, with or without
@@ -38,6 +39,11 @@ include ${TOPDIR}/tools/Config.mk
 
 HOSTOS = ${shell uname -o 2>/dev/null || echo "Other"}
 
+ifeq ($(CONFIG_WINDOWS_MSYS),y)
+  DIRLINK = $(TOPDIR)/tools/copydir.sh
+  DIRUNLINK = $(TOPDIR)/tools/unlink.sh
+endif
+
 ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
   ARCHOPTIMIZATION = -g
 endif