diff --git a/packages/react-devtools-core/webpack.standalone.js b/packages/react-devtools-core/webpack.standalone.js
index b21dfe5180b2e..9818479d1637b 100644
--- a/packages/react-devtools-core/webpack.standalone.js
+++ b/packages/react-devtools-core/webpack.standalone.js
@@ -57,7 +57,11 @@ module.exports = {
           {
             loader: 'css-loader',
             options: {
-              sourceMap: true,
+              // WARNING It's important that we disable CSS source maps for production builds.
+              // This causes style-loader to insert styles via a <style> tag rather than URL.createObjectURL,
+              // which in turn avoids a nasty Electron/Chromium bug that breaks DevTools in Nuclide.
+              // (Calls to URL.createObjectURL seem to crash the webview process.)
+              sourceMap: __DEV__,
               modules: true,
               localIdentName: '[local]___[hash:base64:5]',
             },
diff --git a/shells/browser/shared/webpack.config.js b/shells/browser/shared/webpack.config.js
index dd2acc1f3c917..def3e17b87d53 100644
--- a/shells/browser/shared/webpack.config.js
+++ b/shells/browser/shared/webpack.config.js
@@ -59,7 +59,7 @@ module.exports = {
           {
             loader: 'css-loader',
             options: {
-              sourceMap: true,
+              sourceMap: __DEV__,
               modules: true,
               localIdentName: '[local]___[hash:base64:5]',
             },
diff --git a/shells/dev/webpack.config.js b/shells/dev/webpack.config.js
index 6738e13117462..feefff86b346e 100644
--- a/shells/dev/webpack.config.js
+++ b/shells/dev/webpack.config.js
@@ -57,7 +57,7 @@ const config = {
           {
             loader: 'css-loader',
             options: {
-              sourceMap: true,
+              sourceMap: __DEV__,
               modules: true,
               localIdentName: '[local]___[hash:base64:5]',
             },