diff --git a/reactos/Makefile b/reactos/Makefile
index ccf55988031..b654ebf5e88 100644
--- a/reactos/Makefile
+++ b/reactos/Makefile
@@ -115,7 +115,8 @@ all: makefile.auto
 
 ifeq ($(HOST),)
 ifeq ($(word 1,$(shell gcc -dumpmachine)),mingw32)
-ifeq ($(OSTYPE),msys)
+ifeq ($(findstring msys,$(shell sh --version 2>nul)),msys)
+export OSTYPE = msys
 HOST=mingw32-linux
 else
 HOST=mingw32-windows