diff --git a/makefile.basic b/makefile.basic
index 2ee78a1..f5dec99 100644
--- a/makefile.basic
+++ b/makefile.basic
@@ -16,7 +16,7 @@
 #Makefile to generate a single executable from all sources in SOURCE_DIRS that end in EXT
 
 ifeq ($(OS),Windows_NT)
-	WINDOWS=1
+	WINDOWS::=1
 endif
 
 SOURCE_DIRS::=src