diff --git a/ms/do_win64a.bat b/ms/do_win64a.bat
index 8768dc6..6772390 100755
--- a/ms/do_win64a.bat
+++ b/ms/do_win64a.bat
@@ -1,19 +1,19 @@
-perl util\mkfiles.pl >MINFO
+perl util/mkfiles.pl >MINFO
 
 cmd /c "nasm -f win64 -v" >NUL 2>&1
 if %errorlevel% neq 0 goto ml64
 
-perl ms\uplink-x86_64.pl nasm > ms\uptable.asm
-nasm -f win64 -o ms\uptable.obj ms\uptable.asm
+perl ms/uplink-x86_64.pl nasm > ms/uptable.asm
+nasm -f win64 -o ms/uptable.obj ms/uptable.asm
 goto proceed
 
 :ml64
-perl ms\uplink-x86_64.pl masm > ms\uptable.asm
-ml64 -c -Foms\uptable.obj ms\uptable.asm
+perl ms/uplink-x86_64.pl masm > ms/uptable.asm
+ml64 -c -Foms/uptable.obj ms/uptable.asm
 
 :proceed
-perl util\mk1mf.pl VC-WIN64A >ms\nt.mak
-perl util\mk1mf.pl dll VC-WIN64A >ms\ntdll.mak
+perl util/mk1mf.pl VC-WIN64A >ms/nt.mak
+perl util/mk1mf.pl dll VC-WIN64A >ms/ntdll.mak
 
-perl util\mkdef.pl 32 libeay > ms\libeay32.def
-perl util\mkdef.pl 32 ssleay > ms\ssleay32.def
+perl util/mkdef.pl 32 libeay > ms/libeay32.def
+perl util/mkdef.pl 32 ssleay > ms/ssleay32.def
diff --git a/util/mk1mf.pl b/util/mk1mf.pl
index 72fa089..d98def1 100755
--- a/util/mk1mf.pl
+++ b/util/mk1mf.pl
@@ -233,6 +233,9 @@ else
 	$cflags.=' -DTERMIO';
 	}
 
+# force unix style path separator
+${o} = "/";
+
 $fipsdir =~ s/\//${o}/g;
 
 $out_dir=(defined($VARS{'OUT'}))?$VARS{'OUT'}:$out_def.($debug?".dbg":"");