diff --git a/Libretro/Makefile b/Libretro/Makefile
index 90d4ec6..56bd9bf 100644
--- a/Libretro/Makefile
+++ b/Libretro/Makefile
@@ -180,7 +180,7 @@ else ifneq (,$(findstring windows_msvc2017,$(platform)))
   reg_query = $(call filter_out2,$(subst $2,,$(shell reg query "$2" -v "$1" 2>nul)))
   fix_path = $(subst $(SPACE),\ ,$(subst \,/,$1))
 
-  ProgramFiles86w := $(shell cmd /c "echo %PROGRAMFILES(x86)%")
+  ProgramFiles86w := $(shell cmd //c "echo %PROGRAMFILES(x86)%")
   ProgramFiles86 := $(shell cygpath "$(ProgramFiles86w)")
 
   WindowsSdkDir ?= $(call reg_query,InstallationFolder,HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Microsoft SDKs\Windows\v10.0)