diff --git a/src/auto.ts b/src/auto.ts
index d6f5d25..5d3697f 100644
--- a/src/auto.ts
+++ b/src/auto.ts
@@ -2,10 +2,10 @@ import { normalize, join } from 'pathe'
 import consola from 'consola'
 import chalk from 'chalk'
 import type { PackageJson } from 'pkg-types'
-import { extractExportFilenames, listRecursively } from './utils'
+import { extractExportFilenames, listRecursively, warn } from './utils'
 import { BuildEntry, definePreset, MkdistBuildEntry } from './types'
 
-type InferEntriesResult = { entries: BuildEntry[], cjs?: boolean, dts?: boolean }
+type InferEntriesResult = { entries: BuildEntry[], cjs?: boolean, dts?: boolean, warnings: string[] }
 
 export const autoPreset = definePreset(() => {
   return {
@@ -17,6 +17,9 @@ export const autoPreset = definePreset(() => {
         }
         const sourceFiles = listRecursively(join(ctx.options.rootDir, 'src'))
         const res = inferEntries(ctx.pkg, sourceFiles)
+        for (const message of res.warnings) {
+          warn(ctx, message)
+        }
         ctx.options.entries.push(...res.entries)
         if (res.cjs) {
           ctx.options.rollup.emitCJS = true
@@ -41,6 +44,8 @@ export const autoPreset = definePreset(() => {
  *   - if an array of source files, these will be used directly instead of accessing fs.
  */
 export function inferEntries (pkg: PackageJson, sourceFiles: string[]): InferEntriesResult {
+  const warnings = []
+
   // Come up with a list of all output files & their formats
   const outputs = extractExportFilenames(pkg.exports)
 
@@ -93,7 +98,7 @@ export function inferEntries (pkg: PackageJson, sourceFiles: string[]): InferEnt
     }, undefined)
 
     if (!input) {
-      consola.warn(`could not infer entrypoint for \`${output.file}\``)
+      warnings.push(`Could not find entrypoint for ${output.file}`)
       continue
     }
 
@@ -113,7 +118,7 @@ export function inferEntries (pkg: PackageJson, sourceFiles: string[]): InferEnt
     }
   }
 
-  return { entries, cjs, dts }
+  return { entries, cjs, dts, warnings }
 }
 
 export const getEntrypointPaths = (path: string) => {
diff --git a/src/build.ts b/src/build.ts
index 0974dd4..2c8ad3b 100644
--- a/src/build.ts
+++ b/src/build.ts
@@ -42,6 +42,7 @@ export async function build (rootDir: string, stub: boolean, inputConfig: BuildC
     peerDependencies: [],
     alias: {},
     replace: {},
+    failOnWarn: true,
     rollup: {
       emitCJS: false,
       cjsBridge: false,
@@ -75,6 +76,7 @@ export async function build (rootDir: string, stub: boolean, inputConfig: BuildC
   // Build context
   const ctx: BuildContext = {
     options,
+    warnings: new Set(),
     pkg,
     buildEntries: [],
     usedImports: new Set(),
@@ -182,10 +184,18 @@ export async function build (rootDir: string, stub: boolean, inputConfig: BuildC
 
   // Validate
   validateDependencies(ctx)
-  validatePackage(pkg, rootDir)
+  validatePackage(pkg, rootDir, ctx)
 
   // Call build:done
   await ctx.hooks.callHook('build:done', ctx)
 
   consola.log('')
+
+  if (ctx.warnings.size) {
+    consola.warn('Build is done with some warnings:\n\n' + Array.from(ctx.warnings).map(msg => '- ' + msg).join('\n'))
+    if (ctx.options.failOnWarn) {
+      consola.error('Exiting with code (1). You can change this behavior by setting `failOnWarn: false` .')
+      process.exit(1)
+    }
+  }
 }
diff --git a/src/builder/rollup.ts b/src/builder/rollup.ts
index 7cb91d7..a0d2bb2 100644
--- a/src/builder/rollup.ts
+++ b/src/builder/rollup.ts
@@ -10,9 +10,8 @@ import _esbuild from 'rollup-plugin-esbuild'
 import dts from 'rollup-plugin-dts'
 import replace from '@rollup/plugin-replace'
 import { relative, resolve, dirname } from 'pathe'
-import consola from 'consola'
 import { resolvePath } from 'mlly'
-import { getpkg, tryResolve } from '../utils'
+import { getpkg, tryResolve, warn } from '../utils'
 import type { BuildContext } from '../types'
 import { JSONPlugin } from './plugins/json'
 import { rawPlugin } from './plugins/raw'
@@ -140,7 +139,7 @@ export function getRollupOptions (ctx: BuildContext): RollupOptions {
         return false
       }
       if (!isExplicitExternal) {
-        consola.warn(`Inlining implicit external ${id}`)
+        warn(ctx, `Inlined implicit external ${id}`)
       }
       return isExplicitExternal
     },
diff --git a/src/types.ts b/src/types.ts
index fcb43e5..b6a8121 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -66,6 +66,7 @@ export interface BuildOptions {
   devDependencies: string[]
   alias: { [find: string]: string },
   replace: { [find: string]: string },
+  failOnWarn?: boolean
   rollup: RollupBuildOptions
 }
 
@@ -74,6 +75,7 @@ export interface BuildContext {
   pkg: PackageJson,
   buildEntries: { path: string, bytes?: number, exports?: string[], chunks?: string[] }[]
   usedImports: Set<string>
+  warnings: Set<string>
   hooks: Hookable<BuildHooks>
 }
 
diff --git a/src/utils.ts b/src/utils.ts
index 35e856e..05d6c21 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -5,14 +5,21 @@ import { dirname, resolve } from 'pathe'
 import mkdirp from 'mkdirp'
 import _rimraf from 'rimraf'
 import jiti from 'jiti'
+import consola from 'consola'
 import type { PackageJson } from 'pkg-types'
 import { autoPreset } from './auto'
-import type { BuildPreset, BuildConfig } from './types'
+import type { BuildPreset, BuildConfig, BuildContext } from './types'
 
 export async function ensuredir (path: string) {
   await mkdirp(dirname(path))
 }
 
+export function warn (ctx: BuildContext, message: string) {
+  if (ctx.warnings.has(message)) { return }
+  consola.debug('[unbuild] [warn]', message)
+  ctx.warnings.add(message)
+}
+
 export async function symlink (from: string, to: string, force: boolean = true) {
   await ensuredir(to)
   if (force) {
diff --git a/src/validate.ts b/src/validate.ts
index d64982d..3e564aa 100644
--- a/src/validate.ts
+++ b/src/validate.ts
@@ -1,15 +1,14 @@
 import { existsSync } from 'fs'
 import chalk from 'chalk'
-import consola from 'consola'
 import { resolve } from 'pathe'
 import { PackageJson } from 'pkg-types'
-import { extractExportFilenames, getpkg } from './utils'
+import { extractExportFilenames, getpkg, warn } from './utils'
 import { BuildContext } from './types'
 
 export function validateDependencies (ctx: BuildContext) {
   const usedDependencies = new Set<string>()
   const unusedDependencies = new Set<string>(Object.keys(ctx.pkg.dependencies || {}))
-  const implicitDependnecies = new Set<string>()
+  const implicitDependencies = new Set<string>()
   for (const id of ctx.usedImports) {
     unusedDependencies.delete(id)
     usedDependencies.add(id)
@@ -26,18 +25,18 @@ export function validateDependencies (ctx: BuildContext) {
       !ctx.options.dependencies.includes(getpkg(id)) &&
       !ctx.options.peerDependencies.includes(getpkg(id))
     ) {
-      implicitDependnecies.add(id)
+      implicitDependencies.add(id)
     }
   }
   if (unusedDependencies.size) {
-    consola.warn('Potential unused dependencies found:', Array.from(unusedDependencies).map(id => chalk.cyan(id)).join(', '))
+    warn(ctx, 'Potential unused dependencies found: ' + Array.from(unusedDependencies).map(id => chalk.cyan(id)).join(', '))
   }
-  if (implicitDependnecies.size && !ctx.options.rollup.inlineDependencies) {
-    consola.warn('Potential implicit dependencies found:', Array.from(implicitDependnecies).map(id => chalk.cyan(id)).join(', '))
+  if (implicitDependencies.size && !ctx.options.rollup.inlineDependencies) {
+    warn(ctx, 'Potential implicit dependencies found: ' + Array.from(implicitDependencies).map(id => chalk.cyan(id)).join(', '))
   }
 }
 
-export function validatePackage (pkg: PackageJson, rootDir: string) {
+export function validatePackage (pkg: PackageJson, rootDir: string, ctx: BuildContext) {
   if (!pkg) { return }
 
   const filenames = new Set([
@@ -57,6 +56,6 @@ export function validatePackage (pkg: PackageJson, rootDir: string) {
     }
   }
   if (missingOutputs.length) {
-    consola.warn(`Potential missing package.json files: ${missingOutputs.map(o => chalk.cyan(o)).join(', ')}`)
+    warn(ctx, `Potential missing package.json files: ${missingOutputs.map(o => chalk.cyan(o)).join(', ')}`)
   }
 }
diff --git a/test/auto.test.ts b/test/auto.test.ts
index c6aaad0..a0fd99d 100644
--- a/test/auto.test.ts
+++ b/test/auto.test.ts
@@ -7,7 +7,8 @@ describe('inferEntries', () => {
     expect(result).to.deep.equal({
       cjs: true,
       dts: false,
-      entries: [{ input: 'src/test' }]
+      entries: [{ input: 'src/test' }],
+      warnings: []
     })
   })
 
@@ -15,17 +16,20 @@ describe('inferEntries', () => {
     expect(inferEntries({ bin: 'dist/cli.cjs' }, ['src/', 'src/cli.ts'])).to.deep.equal({
       cjs: true,
       dts: false,
-      entries: [{ input: 'src/cli' }]
+      entries: [{ input: 'src/cli' }],
+      warnings: []
     })
     expect(inferEntries({ bin: { nuxt: 'dist/cli.js' } }, ['src/', 'src/cli.ts'])).to.deep.equal({
       cjs: true,
       dts: false,
-      entries: [{ input: 'src/cli' }]
+      entries: [{ input: 'src/cli' }],
+      warnings: []
     })
     expect(inferEntries({ bin: { nuxt: 'dist/cli.js' }, type: 'module' }, ['src/', 'src/cli.ts'])).to.deep.equal({
       cjs: false,
       dts: false,
-      entries: [{ input: 'src/cli' }]
+      entries: [{ input: 'src/cli' }],
+      warnings: []
     })
   })
 
@@ -34,7 +38,8 @@ describe('inferEntries', () => {
     expect(result).to.deep.equal({
       cjs: false,
       dts: false,
-      entries: [{ input: 'src/test' }]
+      entries: [{ input: 'src/test' }],
+      warnings: []
     })
   })
 
@@ -43,7 +48,8 @@ describe('inferEntries', () => {
     expect(result).to.deep.equal({
       cjs: false,
       dts: false,
-      entries: [{ input: 'src/other/runtime/index' }]
+      entries: [{ input: 'src/other/runtime/index' }],
+      warnings: []
     })
   })
 
@@ -51,20 +57,22 @@ describe('inferEntries', () => {
     expect(inferEntries({ main: 'dist/test.cjs', types: 'custom/handwritten.d.ts' }, ['src/', 'src/test.ts'])).to.deep.equal({
       cjs: true,
       dts: false,
-      entries: [{ input: 'src/test' }
+      entries: [{ input: 'src/test' }],
+      warnings: [
+        'Could not find entrypoint for custom/handwritten.d.ts'
       ]
     })
     expect(inferEntries({ main: 'dist/test.cjs', module: 'dist/test.mjs', types: 'dist/test.d.ts' }, ['src/', 'src/test.ts'])).to.deep.equal({
       cjs: true,
       dts: true,
-      entries: [{ input: 'src/test' }
-      ]
+      entries: [{ input: 'src/test' }],
+      warnings: []
     })
     expect(inferEntries({ main: 'dist/test.cjs', module: 'dist/test.mjs', typings: 'dist/test.d.ts' }, ['src/', 'src/test.ts'])).to.deep.equal({
       cjs: true,
       dts: true,
-      entries: [{ input: 'src/test' }
-      ]
+      entries: [{ input: 'src/test' }],
+      warnings: []
     })
   })
 
@@ -73,7 +81,8 @@ describe('inferEntries', () => {
     expect(result).to.deep.equal({
       cjs: true,
       dts: true,
-      entries: [{ input: 'src/test' }]
+      entries: [{ input: 'src/test' }],
+      warnings: []
     })
   })
 
@@ -81,7 +90,10 @@ describe('inferEntries', () => {
     expect(inferEntries({ exports: 'dist/test.js' }, ['src/', 'src/index.ts'])).to.deep.equal({
       cjs: false,
       entries: [],
-      dts: false
+      dts: false,
+      warnings: [
+        'Could not find entrypoint for dist/test.js'
+      ]
     })
   })
 
@@ -89,7 +101,8 @@ describe('inferEntries', () => {
     expect(inferEntries({ exports: { './*': './*' } }, ['src/', 'src/', 'src/index.ts'])).to.deep.equal({
       cjs: false,
       entries: [],
-      dts: false
+      dts: false,
+      warnings: []
     })
   })
 
@@ -100,7 +113,8 @@ describe('inferEntries', () => {
       entries: [
         { input: 'src/index' },
         { input: 'src/test' }
-      ]
+      ],
+      warnings: []
     })
   })
 
@@ -108,17 +122,20 @@ describe('inferEntries', () => {
     expect(inferEntries({ exports: './dist/runtime/*' }, ['src/', 'src/runtime/', 'src/runtime/test.js'])).to.deep.equal({
       cjs: false,
       dts: false,
-      entries: [{ format: 'esm', input: 'src/runtime/', outDir: './dist/runtime/' }]
+      entries: [{ format: 'esm', input: 'src/runtime/', outDir: './dist/runtime/' }],
+      warnings: []
     })
     expect(inferEntries({ exports: { './runtime/*': './dist/runtime/*.mjs,' } }, ['src/', 'src/runtime/'])).to.deep.equal({
       cjs: false,
       dts: false,
-      entries: [{ format: 'esm', input: 'src/runtime/', outDir: './dist/runtime/' }]
+      entries: [{ format: 'esm', input: 'src/runtime/', outDir: './dist/runtime/' }],
+      warnings: []
     })
     expect(inferEntries({ exports: { './runtime/*': { require: './dist/runtime/*' } } }, ['src/', 'src/runtime/'])).to.deep.equal({
       cjs: true,
       dts: false,
-      entries: [{ format: 'cjs', input: 'src/runtime/', outDir: './dist/runtime/' }]
+      entries: [{ format: 'cjs', input: 'src/runtime/', outDir: './dist/runtime/' }],
+      warnings: []
     })
   })
 })
diff --git a/test/fixture/src/index.ts b/test/fixture/src/index.ts
index 11c4927..78233de 100644
--- a/test/fixture/src/index.ts
+++ b/test/fixture/src/index.ts
@@ -13,3 +13,6 @@ import('os').then(os => console.log(os.arch()))
 import('./test.html').then(console.log)
 
 export const foo = 'bar'
+
+// Failing test
+// export * from 'defu'
diff --git a/test/validate.test.ts b/test/validate.test.ts
index 7c48ebd..c0ee7a9 100644
--- a/test/validate.test.ts
+++ b/test/validate.test.ts
@@ -7,8 +7,9 @@ import { BuildEntry } from '../src/types'
 
 describe('validatePackage', () => {
   it('detects missing files', () => {
-    const logs: string[] = []
-    consola.mock(type => type === 'warn' ? (str: string) => logs.push(str) : () => { })
+    const buildContext = {
+      warnings: new Set()
+    } as any
 
     validatePackage({
       main: './dist/test',
@@ -20,23 +21,25 @@ describe('validatePackage', () => {
         './runtime/*': './runtime/*.mjs',
         '.': { node: './src/index.ts' }
       }
-    }, join(fileURLToPath(import.meta.url), '../fixture'))
+    }, join(fileURLToPath(import.meta.url), '../fixture'), buildContext)
+
+    const warnings = Array.from(buildContext.warnings)
 
-    expect(logs[0]).to.include('Potential missing')
-    expect(logs[0]).not.to.include('src/index.ts')
+    expect(warnings[0]).to.include('Potential missing')
+    expect(warnings[0]).not.to.include('src/index.ts')
 
     for (const file of ['dist/test', 'dist/cli', 'dist/mod', 'runtime']) {
-      expect(logs[0]).to.include(file)
+      expect(warnings[0]).to.include(file)
     }
   })
 })
 
 describe('validateDependecies', () => {
   it('detects implicit deps', () => {
-    const logs: string[] = []
-    consola.mock(type => type === 'warn' ? (str: string) => logs.push(str) : () => { })
+    const warnings = new Set<string>()
 
     validateDependencies({
+      warnings,
       pkg: {},
       buildEntries: [],
       hooks: [] as any,
@@ -64,7 +67,7 @@ describe('validateDependecies', () => {
       }
     })
 
-    expect(logs[0]).to.include('Potential implicit dependencies found:')
+    expect(Array.from(warnings)[0]).to.include('Potential implicit dependencies found:')
   })
 
   it('does not print implicit deps warning for peerDependencies', () => {