diff --git a/packages/react-scripts/config/webpack.config.prod.js b/packages/react-scripts/config/webpack.config.prod.js
index 4d04909a8b461afa8d4479b23243a84ac425e4a2..91cc8cf7c2d8a7cb11ee41c085a2fa48fb51a7eb 100644
--- a/packages/react-scripts/config/webpack.config.prod.js
+++ b/packages/react-scripts/config/webpack.config.prod.js
@@ -134,6 +134,12 @@ module.exports = {
             // Pending further investigation:
             // https://github.com/mishoo/UglifyJS2/issues/2011
             comparisons: false,
+            // Disabled because of an issue with Uglify breaking seemingly valid code:
+            // https://github.com/mishoo/UglifyJS2/issues/3122
+            // although fixed, the fixed version of uglify-es hasn't been release and
+            // it seems like it won't since it is no longer mantained:
+            // https://github.com/mishoo/UglifyJS2/issues/3156
+            reduce_vars: false
           },
           mangle: {
             safari10: true,