diff --git a/src/babelPluginTsdx.ts b/src/babelPluginTsdx.ts
index cc5728d55..665731394 100644
--- a/src/babelPluginTsdx.ts
+++ b/src/babelPluginTsdx.ts
@@ -73,10 +73,6 @@ export const babelPluginTsdx = babelPlugin.custom(() => ({
           name: 'babel-plugin-transform-rename-import',
           replacements,
         },
-        isTruthy(customOptions.defines) && {
-          name: 'babel-plugin-transform-replace-expressions',
-          replace: customOptions.defines,
-        },
         {
           name: 'babel-plugin-transform-async-to-promises',
           inlineHelpers: true,
diff --git a/src/createRollupConfig.ts b/src/createRollupConfig.ts
index 5ea2eb5ae..824ba43d6 100644
--- a/src/createRollupConfig.ts
+++ b/src/createRollupConfig.ts
@@ -189,7 +189,6 @@ export async function createRollupConfig(
           targets: opts.target === 'node' ? { node: '8' } : undefined,
           extractErrors: opts.extractErrors,
           format: opts.format,
-          // defines: opts.defines,
         },
       }),
       opts.env !== undefined &&