diff --git a/packages/react-devtools-core/webpack.backend.js b/packages/react-devtools-core/webpack.backend.js
index f2e85842a6c76..3a27421d94e84 100644
--- a/packages/react-devtools-core/webpack.backend.js
+++ b/packages/react-devtools-core/webpack.backend.js
@@ -44,7 +44,6 @@ module.exports = {
   plugins: [
     new DefinePlugin({
       __DEV__: true,
-      __TEST__: false,
       'process.env.DEVTOOLS_VERSION': `"${DEVTOOLS_VERSION}"`,
       'process.env.GITHUB_URL': `"${GITHUB_URL}"`,
     }),
diff --git a/packages/react-devtools-core/webpack.standalone.js b/packages/react-devtools-core/webpack.standalone.js
index fa3caf4e00faa..d6b41ced0b1f7 100644
--- a/packages/react-devtools-core/webpack.standalone.js
+++ b/packages/react-devtools-core/webpack.standalone.js
@@ -43,7 +43,6 @@ module.exports = {
   plugins: [
     new DefinePlugin({
       __DEV__: false,
-      __TEST__: false,
       'process.env.DEVTOOLS_VERSION': `"${DEVTOOLS_VERSION}"`,
       'process.env.GITHUB_URL': `"${GITHUB_URL}"`,
       'process.env.NODE_ENV': `"${NODE_ENV}"`,
diff --git a/packages/react-devtools-extensions/webpack.backend.js b/packages/react-devtools-extensions/webpack.backend.js
index 8024b373ba67e..03911a31290b2 100644
--- a/packages/react-devtools-extensions/webpack.backend.js
+++ b/packages/react-devtools-extensions/webpack.backend.js
@@ -39,7 +39,6 @@ module.exports = {
   plugins: [
     new DefinePlugin({
       __DEV__: true,
-      __TEST__: false,
       'process.env.DEVTOOLS_VERSION': `"${DEVTOOLS_VERSION}"`,
       'process.env.GITHUB_URL': `"${GITHUB_URL}"`,
     }),
diff --git a/packages/react-devtools-extensions/webpack.config.js b/packages/react-devtools-extensions/webpack.config.js
index 1aa5988a17457..8a362f82fd3db 100644
--- a/packages/react-devtools-extensions/webpack.config.js
+++ b/packages/react-devtools-extensions/webpack.config.js
@@ -44,7 +44,6 @@ module.exports = {
   plugins: [
     new DefinePlugin({
       __DEV__: false,
-      __TEST__: false,
       'process.env.DEVTOOLS_VERSION': `"${DEVTOOLS_VERSION}"`,
       'process.env.GITHUB_URL': `"${GITHUB_URL}"`,
       'process.env.NODE_ENV': `"${NODE_ENV}"`,
diff --git a/packages/react-devtools-inline/webpack.config.js b/packages/react-devtools-inline/webpack.config.js
index bd1966683b92c..32d98a12a1443 100644
--- a/packages/react-devtools-inline/webpack.config.js
+++ b/packages/react-devtools-inline/webpack.config.js
@@ -40,7 +40,6 @@ module.exports = {
   plugins: [
     new DefinePlugin({
       __DEV__,
-      __TEST__: false,
       'process.env.DEVTOOLS_VERSION': `"${DEVTOOLS_VERSION}"`,
       'process.env.GITHUB_URL': `"${GITHUB_URL}"`,
       'process.env.NODE_ENV': `"${NODE_ENV}"`,
diff --git a/packages/react-devtools-shell/webpack.config.js b/packages/react-devtools-shell/webpack.config.js
index 40099b0875e59..0755e4ca572bb 100644
--- a/packages/react-devtools-shell/webpack.config.js
+++ b/packages/react-devtools-shell/webpack.config.js
@@ -43,7 +43,6 @@ const config = {
   plugins: [
     new DefinePlugin({
       __DEV__,
-      __TEST__: false,
       'process.env.GITHUB_URL': `"${GITHUB_URL}"`,
       'process.env.DEVTOOLS_VERSION': `"${DEVTOOLS_VERSION}"`,
     }),