diff --git a/server/store.js b/server/store.js
index 972e3a6..042dbcc 100644
--- a/server/store.js
+++ b/server/store.js
@@ -1,4 +1,8 @@
-const store = require('json-fs-store')('/tmp/pdfer-store/');
+const storeDir = process.env.JSON_STORE || '/tmp/pdfer-store/';
+
+console.log(`using json-store at ${storeDir}`);
+
+const store = require('json-fs-store')(storeDir);
 const { promisify } = require('util');
 
 const list = promisify(store.list);