diff --git a/package-lock.json b/package-lock.json
index c7c7dcf..d55a41a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "@anthropic-ai/sandbox-runtime",
-  "version": "0.0.25",
+  "version": "0.0.26",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
diff --git a/package.json b/package.json
index c0b15b6..adbe5f0 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@anthropic-ai/sandbox-runtime",
-  "version": "0.0.25",
+  "version": "0.0.26",
   "description": "Anthropic Sandbox Runtime (ASRT) - A general-purpose tool for wrapping security boundaries around arbitrary processes",
   "type": "module",
   "main": "./dist/index.js",
diff --git a/src/sandbox/sandbox-utils.ts b/src/sandbox/sandbox-utils.ts
index 8a5b080..6c2d2cc 100644
--- a/src/sandbox/sandbox-utils.ts
+++ b/src/sandbox/sandbox-utils.ts
@@ -298,7 +298,9 @@ export function generateProxyEnvVars(
   httpProxyPort?: number,
   socksProxyPort?: number,
 ): string[] {
-  const envVars: string[] = [`SANDBOX_RUNTIME=1`, `TMPDIR=/tmp/claude`]
+  // Respect CLAUDE_TMPDIR if set, otherwise default to /tmp/claude
+  const tmpdir = process.env.CLAUDE_TMPDIR || '/tmp/claude'
+  const envVars: string[] = [`SANDBOX_RUNTIME=1`, `TMPDIR=${tmpdir}`]
 
   // If no proxy ports provided, return minimal env vars
   if (!httpProxyPort && !socksProxyPort) {