diff --git a/lib/python/qmk/cli/multibuild.py b/lib/python/qmk/cli/multibuild.py
index 46594c0997e..2848a3b8299 100755
--- a/lib/python/qmk/cli/multibuild.py
+++ b/lib/python/qmk/cli/multibuild.py
@@ -76,4 +76,4 @@ all: {keyboard_safe}_binary
             )
             # yapf: enable
 
-    cli.run([make_cmd, '-j', str(cli.args.parallel), '-f', makefile, 'all'], capture_output=False, stdin=DEVNULL)
+    cli.run([make_cmd, '-j', str(cli.args.parallel), '-f', makefile.as_posix(), 'all'], capture_output=False, stdin=DEVNULL)