diff --git a/packages/opencode/src/bun/index.ts b/packages/opencode/src/bun/index.ts
index bdb7cff78..79aaae2bc 100644
--- a/packages/opencode/src/bun/index.ts
+++ b/packages/opencode/src/bun/index.ts
@@ -66,14 +66,14 @@ export namespace BunProc {
     using _ = await Lock.write("bun-install")
 
     const mod = path.join(Global.Path.cache, "node_modules", pkg)
-    const pkgjson = Bun.file(path.join(Global.Path.cache, "package.json"))
-    const parsed = await pkgjson.json().catch(async () => {
-      const result = { dependencies: {} }
-      await Bun.write(pkgjson.name!, JSON.stringify(result, null, 2))
+    const pkgjsonPath = path.join(Global.Path.cache, "package.json")
+    const parsed = await Filesystem.readJson<{ dependencies: Record<string, string> }>(pkgjsonPath).catch(async () => {
+      const result = { dependencies: {} as Record<string, string> }
+      await Filesystem.writeJson(pkgjsonPath, result)
       return result
     })
-    const dependencies = parsed.dependencies ?? {}
-    if (!parsed.dependencies) parsed.dependencies = dependencies
+    if (!parsed.dependencies) parsed.dependencies = {} as Record<string, string>
+    const dependencies = parsed.dependencies
     const modExists = await Filesystem.exists(mod)
     const cachedVersion = dependencies[pkg]
 
@@ -123,15 +123,16 @@ export namespace BunProc {
     // This ensures subsequent starts use the cached version until explicitly updated
     let resolvedVersion = version
     if (version === "latest") {
-      const installedPkgJson = Bun.file(path.join(mod, "package.json"))
-      const installedPkg = await installedPkgJson.json().catch(() => null)
+      const installedPkg = await Filesystem.readJson<{ version?: string }>(path.join(mod, "package.json")).catch(
+        () => null,
+      )
       if (installedPkg?.version) {
         resolvedVersion = installedPkg.version
       }
     }
 
     parsed.dependencies[pkg] = resolvedVersion
-    await Bun.write(pkgjson.name!, JSON.stringify(parsed, null, 2))
+    await Filesystem.writeJson(pkgjsonPath, parsed)
     return mod
   }
 }