diff --git a/src/index.ts b/src/index.ts
index a00102d3..ce59651a 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -119,7 +119,27 @@ const normalizeOptions = async (
   }
 
   if (Array.isArray(entry)) {
-    const matcher = picomatch(entry, { windows: process.platform === 'win32' })
+    // using a directory as entry should match all files inside it
+    const expandedEntries = entry.map((pattern) => {
+      if (!pattern.endsWith('**')) {
+        return `${pattern}/**`
+      }
+      return pattern
+    })
+    const matchPatterns: string[] = []
+    const ignorePatterns: string[] = []
+    for (const pattern of expandedEntries) {
+      if (pattern.startsWith('!') && pattern[1] !== '(') {
+        ignorePatterns.push(pattern.slice(1))
+      } else {
+        matchPatterns.push(pattern)
+      }
+    }
+    const matcher = picomatch(matchPatterns, {
+      ignore: ignorePatterns,
+      dot: true,
+      windows: process.platform === 'win32',
+    })
     options.entry = await new fdir()
       .withRelativePaths()
       .filter((file) => matcher(file))
diff --git a/test/index.test.ts b/test/index.test.ts
index 5b07554f..d2f771c4 100644
--- a/test/index.test.ts
+++ b/test/index.test.ts
@@ -901,3 +901,19 @@ test('generate sourcemap with --treeshake', async () => {
       }),
   )
 })
+
+test('should not throw when having directories as entry', async () => {
+  const sourceCode = 'export const h = "h"'
+
+  expect(
+    run(
+      getTestName(),
+      {
+        'src/input.ts': sourceCode,
+      },
+      {
+        entry: ['src'],
+      },
+    ),
+  ).resolves
+})