diff --git a/lib/tbb_2020.3/build/windows.inc b/lib/tbb_2020.3/build/windows.inc
index 186f4bd99ca..8c8ca23c1b5 100644
--- a/lib/tbb_2020.3/build/windows.inc
+++ b/lib/tbb_2020.3/build/windows.inc
@@ -26,11 +26,11 @@ detect_js = $(shell cmd //C "cscript //NoLogo //E:jscript $(tbb_root)/build/dete
 
 # TODO give an error if archs doesn't match
 ifndef arch
-  export arch:=$(call detect_js, //arch $(compiler))
+  export arch:=$(call detect_js, /arch $(compiler))
 endif
 
 ifndef runtime
-  export runtime:=$(call detect_js, //runtime $(compiler))
+  export runtime:=$(call detect_js, /runtime $(compiler))
 endif
 
 native_compiler := cl