diff --git a/SCons/Config/gnu b/SCons/Config/gnu
index 99b9f12c..f2cb3697 100644
--- a/SCons/Config/gnu
+++ b/SCons/Config/gnu
@@ -237,7 +237,7 @@ def check_big_endian(ctx):
 
 conf = defenv.Configure(custom_tests = { 'CheckBigEndian' : check_big_endian })
 if conf.CheckBigEndian():
-	makensis_env.Append(CPPFLAGS = ['__BIG_ENDIAN__'])
+	makensis_env.Append(CPPDEFINES = ['__BIG_ENDIAN__'])
 conf.Finish()
 
 ### return