diff --git a/packages/next/build/entries.ts b/packages/next/build/entries.ts
index 90158e859616220..b9705c2d0a964a8 100644
--- a/packages/next/build/entries.ts
+++ b/packages/next/build/entries.ts
@@ -91,7 +91,7 @@ export function createEntrypoints(
     buildId,
     assetPrefix: config.assetPrefix,
     generateEtags: config.generateEtags ? 'true' : '',
-    poweredByHeader: config.poweredByHeader,
+    poweredByHeader: config.poweredByHeader ? 'true' : '',
     canonicalBase: config.amp.canonicalBase || '',
     basePath: config.basePath,
     runtimeConfig: hasRuntimeConfig
diff --git a/packages/next/server/config-shared.ts b/packages/next/server/config-shared.ts
index cbe5849346e5d7d..d3322d338e51aed 100644
--- a/packages/next/server/config-shared.ts
+++ b/packages/next/server/config-shared.ts
@@ -48,6 +48,22 @@ export type NextConfig = { [key: string]: any } & {
   webpack5?: false
   excludeDefaultMomentLocales?: boolean
 
+  webpack?:
+    | ((
+        config: any,
+        context: {
+          dir: string
+          dev: boolean
+          isServer: boolean
+          buildId: string
+          config: NextConfigComplete
+          defaultLoaders: { babel: any }
+          totalPages: number
+          webpack: any
+        }
+      ) => any)
+    | null
+
   trailingSlash?: boolean
   env?: { [key: string]: string }
   distDir?: string
@@ -58,6 +74,7 @@ export type NextConfig = { [key: string]: any } & {
   generateEtags?: boolean
   pageExtensions?: string[]
   compress?: boolean
+  poweredByHeader?: boolean
   images?: ImageConfig
   devIndicators?: {
     buildActivity?: boolean