diff --git a/lib/mixins/pool.js b/lib/mixins/pool.js
index 5d83ade..a6d43d7 100644
--- a/lib/mixins/pool.js
+++ b/lib/mixins/pool.js
@@ -12,7 +12,7 @@ module.exports = class Pool {
     const Singular = capitalize(singular)
     const Plural = capitalize(plural)
 
-    const source = `class ${Plural}Pool extends Mixin {
+    const source = `(class ${Plural}Pool extends Mixin {
       init${Plural}Pool (${plural}Class, ${plural}Container) {
         this.${plural}Class = ${plural}Class
         this.${plural}Container = ${plural}Container
@@ -56,7 +56,7 @@ module.exports = class Pool {
         this.used${Plural} = []
         return this.unused${Plural} = []
       }
-    }`
+    })`
 
     const sandbox = {Mixin, atom, console}
     const context = vm.createContext(sandbox)