diff --git a/lib/toml-parser.js b/lib/toml-parser.js
index 1acba00..d564683 100644
--- a/lib/toml-parser.js
+++ b/lib/toml-parser.js
@@ -169,7 +169,7 @@ const _inspect = (utilInspect && utilInspect.custom) || 'inspect'
 class BoxedBigInt {
   constructor (value) {
     try {
-      this.value = global.BigInt(value)
+      this.value = global.BigInt.asIntN(64, value)
     } catch (_) {
       /* istanbul ignore next */
       this.value = null