diff --git a/Makefile b/Makefile
index 0ec1d6ae..6f2c35d2 100755
--- a/Makefile
+++ b/Makefile
@@ -82,7 +82,7 @@ endif
 
 # Special case for MinGW
 ifneq (,$(findstring MINGW,$(YQ2_OSTYPE)))
-YQ2_OSTYPE ?= Windows
+YQ2_OSTYPE := Windows
 endif
 
 # Detect the architecture