diff --git a/packages/xsnap/src/xsnap.js b/packages/xsnap/src/xsnap.js
index 6b38e5e49a0..da1d79ce9fd 100644
--- a/packages/xsnap/src/xsnap.js
+++ b/packages/xsnap/src/xsnap.js
@@ -114,7 +114,7 @@ export function xsnap(options) {
     stdio: ['ignore', stdout, stderr, 'pipe', 'pipe'],
   });
 
-  xsnapProcess.on('exit', (code, signal) => {
+  xsnapProcess.once('exit', (code, signal) => {
     if (code === 0) {
       vatExit.resolve();
     } else if (signal !== null) {