diff --git a/implementations/javascript/package.json b/implementations/javascript/package.json
index a1c98d9..88a42ab 100644
--- a/implementations/javascript/package.json
+++ b/implementations/javascript/package.json
@@ -1,6 +1,6 @@
 {
   "name": "preserves",
-  "version": "0.0.9",
+  "version": "0.0.10",
   "description": "Experimental data serialization format",
   "homepage": "https://gitlab.com/tonyg/preserves",
   "license": "MIT",
diff --git a/implementations/javascript/src/symbols.js b/implementations/javascript/src/symbols.js
index 8e7e700..0b28e47 100644
--- a/implementations/javascript/src/symbols.js
+++ b/implementations/javascript/src/symbols.js
@@ -1,8 +1,8 @@
 "use strict";
 // Symbols for various Preserves protocols.
 
-const PreserveOn = Symbol('PreserveOn');
-const AsPreserve = Symbol('AsPreserve');
+const PreserveOn = Symbol.for('PreserveOn');
+const AsPreserve = Symbol.for('AsPreserve');
 
 Object.assign(module.exports, {
   PreserveOn,