diff --git a/lib/pipeline/webpack.config.js b/lib/pipeline/webpack.config.js
index fe914d85..e44bacf6 100644
--- a/lib/pipeline/webpack.config.js
+++ b/lib/pipeline/webpack.config.js
@@ -216,6 +216,10 @@ if (isTypeScriptEnabled) {
   base.resolve.extensions.push('.ts', '.tsx');
 }
 
+if (isFlowEnabled && isTypeScriptEnabled) {
+  throw new Error('isFlowEnabled and isTypeScriptEnabled cannot both be true');
+}
+
 // development config
 // -----------------------------------------------------------------------------