diff --git a/packages/babel-core/src/transformation/normalize-file.js b/packages/babel-core/src/transformation/normalize-file.js
index aca84e1e..17d7dfad 100644
--- a/packages/babel-core/src/transformation/normalize-file.js
+++ b/packages/babel-core/src/transformation/normalize-file.js
@@ -12,7 +12,7 @@ import File from "./file/file";
 import parser from "../parser";
 
 const debug = buildDebug("babel:transform:file");
-const LARGE_INPUT_SOURCEMAP_THRESHOLD = 1_000_000;
+const LARGE_INPUT_SOURCEMAP_THRESHOLD = 1000000;
 
 export type NormalizedFile = {
   code: string,
diff --git a/packages/babel-generator/src/index.js b/packages/babel-generator/src/index.js
index da2eb2b3..4353289f 100644
--- a/packages/babel-generator/src/index.js
+++ b/packages/babel-generator/src/index.js
@@ -79,7 +79,7 @@ function normalizeOptions(code, opts): Format {
   }
 
   if (format.compact === "auto") {
-    format.compact = code.length > 500_000; // 500KB
+    format.compact = code.length > 500000; // 500KB
 
     if (format.compact) {
       console.error(
diff --git a/packages/babel-traverse/src/context.js b/packages/babel-traverse/src/context.js
index be41ecc9..fffbf54e 100644
--- a/packages/babel-traverse/src/context.js
+++ b/packages/babel-traverse/src/context.js
@@ -117,7 +117,7 @@ export default class TraversalContext {
       // this path no longer belongs to the tree
       if (path.key === null) continue;
 
-      if (testing && queue.length >= 10_000) {
+      if (testing && queue.length >= 10000) {
         this.trap = true;
       }