diff --git a/gdf.js b/gdf.js
index 9964ecf..e02405e 100755
--- a/gdf.js
+++ b/gdf.js
@@ -203,23 +203,28 @@ export class GDF {
   // Experimental nextjs generation?
   get nextjsGeneration() {
     if (!this.nextjs) return false
-    if (!this.#pj.scripts.build === 'next build') return false
-    if (!this.#pj.dependencies.next) return false
+    // only `next build`, optionally with flags; anything more is a custom build
+    if (!/^next build(\s+-[-\w=.]+)*$/.test(this.#pj.scripts?.build?.trim() ?? '')) return false
+    // standalone images contain neither the next CLI nor the sources
+    if (this.standaloneNextjs) return false
     const version = this.#pj.dependencies.next.match(/\d[.\d]*/)
-    if (!version || version[0] < '14.2') return false
+    if (!version) return false
+    const [major, minor = 0] = version[0].split('.').map(Number)
+    if (major < 14 || (major === 14 && minor < 2)) return false
     return true
   }
 
   get standaloneNextjs() {
     if (!this.nextjs) return false
 
-    if (fs.existsSync(path.join(this._appdir, 'next.config.mjs'))) {
-      const config = fs.readFileSync(path.join(this._appdir, 'next.config.mjs'), 'utf-8')
+    for (const ext of ['mjs', 'js', 'cjs', 'ts', 'mts']) {
+      const file = path.join(this._appdir, `next.config.${ext}`)
+      if (!fs.existsSync(file)) continue
+      const config = fs.readFileSync(file, 'utf-8')
       return /output\s*:\s*(["'`])standalone\1/.test(config)
-    } else if (fs.existsSync(path.join(this._appdir, 'next.config.js'))) {
-      const config = fs.readFileSync(path.join(this._appdir, 'next.config.js'), 'utf-8')
-      return /output\s*:\s*(["'`])standalone\1/.test(config)
-    } else return false
+    }
+
+    return false
   }
 
   // Does this application use trpc?
diff --git a/test/frameworks/next-build-flags/.dockerignore b/test/frameworks/next-build-flags/.dockerignore
new file mode 100644
index 0000000..fd3dbb5
--- /dev/null
+++ b/test/frameworks/next-build-flags/.dockerignore
@@ -0,0 +1,36 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+.yarn/install-state.gz
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# local env files
+.env*.local
+
+# vercel
+.vercel
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts
diff --git a/test/frameworks/next-build-flags/Dockerfile b/test/frameworks/next-build-flags/Dockerfile
new file mode 100644
index 0000000..07ada70
--- /dev/null
+++ b/test/frameworks/next-build-flags/Dockerfile
@@ -0,0 +1,48 @@
+# syntax = docker/dockerfile:1
+
+# Adjust NODE_VERSION as desired
+ARG NODE_VERSION=xxx
+FROM node:${NODE_VERSION}-slim AS base
+
+LABEL fly_launch_runtime="Next.js"
+
+# Next.js app lives here
+WORKDIR /app
+
+# Set production environment
+ENV NODE_ENV="production"
+
+
+# Throw-away build stage to reduce size of final image
+FROM base AS build
+
+# Install packages needed to build node modules
+RUN apt-get update -qq && \
+    apt-get install --no-install-recommends -y build-essential node-gyp pkg-config python-is-python3
+
+# Install node modules
+COPY package-lock.json package.json ./
+RUN npm ci --include=dev
+
+# Copy application code
+COPY . .
+
+# Build application
+RUN npx next build --experimental-build-mode compile
+
+# Remove development dependencies
+RUN npm prune --omit=dev
+
+
+# Final stage for app image
+FROM base
+
+# Copy built application
+COPY --from=build /app /app
+
+# Entrypoint sets up the container.
+ENTRYPOINT [ "/app/docker-entrypoint.js" ]
+
+# Start the server by default, this can be overwritten at runtime
+EXPOSE 3000
+CMD [ "npm", "run", "start" ]
diff --git a/test/frameworks/next-standalone/docker-entrypoint.js b/test/frameworks/next-build-flags/docker-entrypoint.js
similarity index 90%
rename from test/frameworks/next-standalone/docker-entrypoint.js
rename to test/frameworks/next-build-flags/docker-entrypoint.js
index 91b89a3..49e5199 100755
--- a/test/frameworks/next-standalone/docker-entrypoint.js
+++ b/test/frameworks/next-build-flags/docker-entrypoint.js
@@ -6,7 +6,7 @@ const env = { ...process.env }
 
 ;(async() => {
   // If running the web server then prerender pages
-  if (process.argv.slice(-2).join(' ') === 'node server.js') {
+  if (process.argv.slice(-3).join(' ') === 'npm run start') {
     await exec('npx next build --experimental-build-mode generate')
   }
 
diff --git a/test/frameworks/next-build-flags/package-lock.json b/test/frameworks/next-build-flags/package-lock.json
new file mode 100644
index 0000000..0985ee8
--- /dev/null
+++ b/test/frameworks/next-build-flags/package-lock.json
@@ -0,0 +1,6 @@
+{
+  "name": "standalone-next-js-test",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {}
+}
diff --git a/test/frameworks/next-build-flags/package.json b/test/frameworks/next-build-flags/package.json
new file mode 100644
index 0000000..349e21f
--- /dev/null
+++ b/test/frameworks/next-build-flags/package.json
@@ -0,0 +1,27 @@
+{
+  "name": "standalone-next-js-test",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "next dev",
+    "build": "next build --turbopack",
+    "start": "next start",
+    "lint": "next lint"
+  },
+  "dependencies": {
+    "next": "14.2.1",
+    "react": "^18",
+    "react-dom": "^18"
+  },
+  "devDependencies": {
+    "@flydotio/dockerfile": "^0.5.5",
+    "@types/node": "^20",
+    "@types/react": "^18",
+    "@types/react-dom": "^18",
+    "eslint": "^8",
+    "eslint-config-next": "14.2.1",
+    "postcss": "^8",
+    "tailwindcss": "^3.4.1",
+    "typescript": "^5"
+  }
+}
diff --git a/test/frameworks/next-custom-build/.dockerignore b/test/frameworks/next-custom-build/.dockerignore
new file mode 100644
index 0000000..fd3dbb5
--- /dev/null
+++ b/test/frameworks/next-custom-build/.dockerignore
@@ -0,0 +1,36 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+.yarn/install-state.gz
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# local env files
+.env*.local
+
+# vercel
+.vercel
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts
diff --git a/test/frameworks/next-custom-build/Dockerfile b/test/frameworks/next-custom-build/Dockerfile
new file mode 100644
index 0000000..c06933a
--- /dev/null
+++ b/test/frameworks/next-custom-build/Dockerfile
@@ -0,0 +1,45 @@
+# syntax = docker/dockerfile:1
+
+# Adjust NODE_VERSION as desired
+ARG NODE_VERSION=xxx
+FROM node:${NODE_VERSION}-slim AS base
+
+LABEL fly_launch_runtime="Next.js"
+
+# Next.js app lives here
+WORKDIR /app
+
+# Set production environment
+ENV NODE_ENV="production"
+
+
+# Throw-away build stage to reduce size of final image
+FROM base AS build
+
+# Install packages needed to build node modules
+RUN apt-get update -qq && \
+    apt-get install --no-install-recommends -y build-essential node-gyp pkg-config python-is-python3
+
+# Install node modules
+COPY package-lock.json package.json ./
+RUN npm ci --include=dev
+
+# Copy application code
+COPY . .
+
+# Build application
+RUN npm run build
+
+# Remove development dependencies
+RUN npm prune --omit=dev
+
+
+# Final stage for app image
+FROM base
+
+# Copy built application
+COPY --from=build /app /app
+
+# Start the server by default, this can be overwritten at runtime
+EXPOSE 3000
+CMD [ "npm", "run", "start" ]
diff --git a/test/frameworks/next-custom-build/package-lock.json b/test/frameworks/next-custom-build/package-lock.json
new file mode 100644
index 0000000..0985ee8
--- /dev/null
+++ b/test/frameworks/next-custom-build/package-lock.json
@@ -0,0 +1,6 @@
+{
+  "name": "standalone-next-js-test",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {}
+}
diff --git a/test/frameworks/next-custom-build/package.json b/test/frameworks/next-custom-build/package.json
new file mode 100644
index 0000000..540d510
--- /dev/null
+++ b/test/frameworks/next-custom-build/package.json
@@ -0,0 +1,27 @@
+{
+  "name": "standalone-next-js-test",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "next dev",
+    "build": "next build && node scripts/postbuild.js",
+    "start": "next start",
+    "lint": "next lint"
+  },
+  "dependencies": {
+    "next": "14.2.1",
+    "react": "^18",
+    "react-dom": "^18"
+  },
+  "devDependencies": {
+    "@flydotio/dockerfile": "^0.5.5",
+    "@types/node": "^20",
+    "@types/react": "^18",
+    "@types/react-dom": "^18",
+    "eslint": "^8",
+    "eslint-config-next": "14.2.1",
+    "postcss": "^8",
+    "tailwindcss": "^3.4.1",
+    "typescript": "^5"
+  }
+}
diff --git a/test/frameworks/next-standalone-ts/.dockerignore b/test/frameworks/next-standalone-ts/.dockerignore
new file mode 100644
index 0000000..fd3dbb5
--- /dev/null
+++ b/test/frameworks/next-standalone-ts/.dockerignore
@@ -0,0 +1,36 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+.yarn/install-state.gz
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# local env files
+.env*.local
+
+# vercel
+.vercel
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts
diff --git a/test/frameworks/next-standalone-ts/Dockerfile b/test/frameworks/next-standalone-ts/Dockerfile
new file mode 100644
index 0000000..a6afec8
--- /dev/null
+++ b/test/frameworks/next-standalone-ts/Dockerfile
@@ -0,0 +1,47 @@
+# syntax = docker/dockerfile:1
+
+# Adjust NODE_VERSION as desired
+ARG NODE_VERSION=xxx
+FROM node:${NODE_VERSION}-slim AS base
+
+LABEL fly_launch_runtime="Next.js"
+
+# Next.js app lives here
+WORKDIR /app
+
+# Set production environment
+ENV NODE_ENV="production"
+
+
+# Throw-away build stage to reduce size of final image
+FROM base AS build
+
+# Install packages needed to build node modules
+RUN apt-get update -qq && \
+    apt-get install --no-install-recommends -y build-essential node-gyp pkg-config python-is-python3
+
+# Install node modules
+COPY package-lock.json package.json ./
+RUN npm ci --include=dev
+
+# Copy application code
+COPY . .
+
+# Build application
+RUN npm run build
+
+# Remove development dependencies
+RUN npm prune --omit=dev
+
+
+# Final stage for app image
+FROM base
+
+# Copy built application
+COPY --from=build /app/.next/standalone /app
+COPY --from=build /app/.next/static /app/.next/static
+COPY --from=build /app/public /app/public
+
+# Start the server by default, this can be overwritten at runtime
+EXPOSE 3000
+CMD [ "node", "server.js" ]
diff --git a/test/frameworks/next-standalone-ts/next.config.ts b/test/frameworks/next-standalone-ts/next.config.ts
new file mode 100644
index 0000000..bff4933
--- /dev/null
+++ b/test/frameworks/next-standalone-ts/next.config.ts
@@ -0,0 +1,7 @@
+import type { NextConfig } from "next";
+
+const nextConfig: NextConfig = {
+  output: "standalone"
+};
+
+export default nextConfig;
diff --git a/test/frameworks/next-standalone-ts/package-lock.json b/test/frameworks/next-standalone-ts/package-lock.json
new file mode 100644
index 0000000..0985ee8
--- /dev/null
+++ b/test/frameworks/next-standalone-ts/package-lock.json
@@ -0,0 +1,6 @@
+{
+  "name": "standalone-next-js-test",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {}
+}
diff --git a/test/frameworks/next-standalone-ts/package.json b/test/frameworks/next-standalone-ts/package.json
new file mode 100644
index 0000000..90a413d
--- /dev/null
+++ b/test/frameworks/next-standalone-ts/package.json
@@ -0,0 +1,27 @@
+{
+  "name": "standalone-next-js-test",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "next dev",
+    "build": "next build",
+    "start": "next start",
+    "lint": "next lint"
+  },
+  "dependencies": {
+    "next": "14.2.1",
+    "react": "^18",
+    "react-dom": "^18"
+  },
+  "devDependencies": {
+    "@flydotio/dockerfile": "^0.5.5",
+    "@types/node": "^20",
+    "@types/react": "^18",
+    "@types/react-dom": "^18",
+    "eslint": "^8",
+    "eslint-config-next": "14.2.1",
+    "postcss": "^8",
+    "tailwindcss": "^3.4.1",
+    "typescript": "^5"
+  }
+}
diff --git a/test/frameworks/next-standalone/Dockerfile b/test/frameworks/next-standalone/Dockerfile
index f22ed4e..a6afec8 100644
--- a/test/frameworks/next-standalone/Dockerfile
+++ b/test/frameworks/next-standalone/Dockerfile
@@ -28,7 +28,7 @@ RUN npm ci --include=dev
 COPY . .
 
 # Build application
-RUN npx next build --experimental-build-mode compile
+RUN npm run build
 
 # Remove development dependencies
 RUN npm prune --omit=dev
@@ -42,9 +42,6 @@ COPY --from=build /app/.next/standalone /app
 COPY --from=build /app/.next/static /app/.next/static
 COPY --from=build /app/public /app/public
 
-# Entrypoint sets up the container.
-ENTRYPOINT [ "/app/docker-entrypoint.js" ]
-
 # Start the server by default, this can be overwritten at runtime
 EXPOSE 3000
 CMD [ "node", "server.js" ]