diff --git a/Makefile b/Makefile
index b5124872..0ae174b9 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,7 @@ PREFIX ?= /usr/local
 # - compile generates .pyd instead of .so
 # - venv with --sytem-site-packages has issues on windows as well...
 
-ifeq ($(shell uname -o), Msys)
+ifeq ($(OSTYPE), msys)
 	BIN = Scripts
 	SO = *.pyd
 	VENV_OPTIONS =