diff --git a/src/libretro/Makefile b/src/libretro/Makefile
index 63875d65..08de8f4b 100644
--- a/src/libretro/Makefile
+++ b/src/libretro/Makefile
@@ -450,7 +450,7 @@ 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)