diff --git a/packages/opencode/src/util/which.ts b/packages/opencode/src/util/which.ts
index 225763081c..2e40739148 100644
--- a/packages/opencode/src/util/which.ts
+++ b/packages/opencode/src/util/which.ts
@@ -3,8 +3,8 @@ import path from "path"
 import { Global } from "../global"
 
 export function which(cmd: string, env?: NodeJS.ProcessEnv) {
-  const base = env?.PATH ?? env?.Path ?? process.env.PATH ?? process.env.Path
-  const full = base + path.delimiter + Global.Path.bin
+  const base = env?.PATH ?? env?.Path ?? process.env.PATH ?? process.env.Path ?? ""
+  const full = base ? base + path.delimiter + Global.Path.bin : Global.Path.bin
   const result = whichPkg.sync(cmd, {
     nothrow: true,
     path: full,