diff --git a/src/hooks/write-existing-file-guard/index.ts b/src/hooks/write-existing-file-guard/index.ts
index 1256b241..1e8ca751 100644
--- a/src/hooks/write-existing-file-guard/index.ts
+++ b/src/hooks/write-existing-file-guard/index.ts
@@ -1,6 +1,6 @@
 import type { Hooks, PluginInput } from "@opencode-ai/plugin"
 import { existsSync } from "fs"
-import { resolve, isAbsolute, join, sep } from "path"
+import { resolve, isAbsolute, join, normalize, sep } from "path"
 import { log } from "../../shared"
 
 export function createWriteExistingFileGuardHook(ctx: PluginInput): Hooks {
@@ -17,7 +17,7 @@ export function createWriteExistingFileGuardHook(ctx: PluginInput): Hooks {
         return
       }
 
-      const resolvedPath = isAbsolute(filePath) ? filePath : resolve(ctx.directory, filePath)
+      const resolvedPath = normalize(isAbsolute(filePath) ? filePath : resolve(ctx.directory, filePath))
 
       if (existsSync(resolvedPath)) {
         const sisyphusRoot = join(ctx.directory, ".sisyphus") + sep