diff --git a/packages/core/src/config.ts b/packages/core/src/config.ts
index 1d7cf00e8..8442fc3c7 100644
--- a/packages/core/src/config.ts
+++ b/packages/core/src/config.ts
@@ -967,15 +967,13 @@ const composeEntryConfig = async (
     const resolvedEntries: Record<string, string> = {};
 
     const resolveOutBase = async (resolvedEntryFiles: string[]) => {
+      if (userOutBase !== undefined) {
+        return path.resolve(root, userOutBase);
+      }
       // Similar to `rootDir` in tsconfig and `outbase` in esbuild.
-      const lcp = await calcLongestCommonPath(resolvedEntryFiles);
-      // Using the longest common path of all non-declaration input files by default.
-      const outBase = userOutBase
-        ? path.resolve(root, userOutBase)
-        : lcp === null
-          ? root
-          : lcp;
-      return outBase;
+      // Using the longest common path of all non-declaration input files if not specified.
+      const lcp = (await calcLongestCommonPath(resolvedEntryFiles)) ?? root;
+      return lcp;
     };
 
     for (const key of Object.keys(entries)) {
diff --git a/website/docs/zh/config/lib/out-base.mdx b/website/docs/zh/config/lib/out-base.mdx
index b502e1818..c12a28a59 100644
--- a/website/docs/zh/config/lib/out-base.mdx
+++ b/website/docs/zh/config/lib/out-base.mdx
@@ -28,7 +28,7 @@
         └── index.ts
 ```
 
-如果未指定输出基础目录，则默认使用所有输入入口点路径的最近公共祖先目录，即 `src/utils`，最终的文件输出结构为：
+如果未指定基础输出目录，则默认使用所有输入入口文件路径的最近公共祖先目录，即 `src/utils`，最终的文件输出结构为：
 
 ```txt
 dist