diff --git a/engine/src/flutter/tools/gn b/engine/src/flutter/tools/gn
index 74bc55bc9b..923a12f6de 100755
--- a/engine/src/flutter/tools/gn
+++ b/engine/src/flutter/tools/gn
@@ -84,7 +84,7 @@ def to_gn_args(args):
       # There is no point in enabling LTO in unoptimized builds.
       enable_lto = False
 
-    if args.target_os != 'win':
+    if not sys.platform.startswith('win'):
       # The GN arg is not available in the windows toolchain.
       gn_args['enable_lto'] = enable_lto