diff --git a/lib/index.js b/lib/index.js
index 4bf5c48..8817986 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -469,7 +469,7 @@ function main() {
                 contents: insertLf(key, false, true),
                 options: {
                     mode: 0o400,
-                    flag: "ax",
+                    flag: "wx",
                 },
             });
         }
diff --git a/src/main.ts b/src/main.ts
index 0187a72..0764350 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -62,7 +62,7 @@ function main(): void
 				contents: insertLf(key, false, true),
 				options: {
 					mode: 0o400,
-					flag: "ax",
+					flag: "wx",
 				},
 			});
 		}