diff --git a/my-blog/content/posts/2025-09-05-plc.md b/my-blog/content/posts/2025-09-05-plc.md
index d93f41f..076c25e 100644
--- a/my-blog/content/posts/2025-09-05-plc.md
+++ b/my-blog/content/posts/2025-09-05-plc.md
@@ -28,6 +28,13 @@ $ goat plc update did:plc:vzsvtbtbnwn22xjqhcu3vd6y \
   --handle syui.syui.ai \
   --pds https://syu.is \
   --atproto-key did:key:zQ3shZj81oA4A9CmUQgYUv97nFdd7m5qNaRMyG16XZixytTmQ > plc_operation_syui.json
+
+# もしミスった時は前の操作を無効化して再実行
+goat plc update did:plc:vzsvtbtbnwn22xjqhcu3vd6y \
+  --handle syui.syui.ai \
+  --pds https://syu.is \
+  --atproto-key did:key:zQ3shZj81oA4A9CmUQgYUv97nFdd7m5qNaRMyG16XZixytTmQ \
+  --prev "bafyreifomvmymylntowv2mbyvg5i7wgv375757l574gevcs7qbysbqizk4" > plc_operation_syui_nullify.json
 ```
 
 ```sh