diff --git a/src/utils/getFilenameFromUrl.js b/src/utils/getFilenameFromUrl.js
index d54bd749a..a71f9a94a 100644
--- a/src/utils/getFilenameFromUrl.js
+++ b/src/utils/getFilenameFromUrl.js
@@ -50,7 +50,6 @@ class FilenameError extends Error {
   }
 }
 
-// TODO fix redirect logic when `/` at the end, like https://github.com/pillarjs/send/blob/master/index.js#L586
 /**
  * @template {IncomingMessage} Request
  * @template {ServerResponse} Response
@@ -110,13 +109,26 @@ function getFilenameFromUrl(context, url) {
         throw new FilenameError("Forbidden", 403);
       }
 
-      // Strip the `pathname` property from the `publicPath` option from the start of requested url
-      // `/complex/foo.js` => `foo.js`
-      // and add outputPath
-      // `foo.js` => `/home/user/my-project/dist/foo.js`
+      let index;
+
+      if (pathname && pathname.endsWith("/")) {
+        if (options.index === false) {
+          return;
+        }
+        index =
+          typeof options.index === "string" ? options.index : "index.html";
+      }
+
+      // Builds the absolute path of the file to serve:
+      // - If the URL ends with '/', appends the index file (index.html or custom) to the directory path.
+      // - If the URL does not end with '/', only joins the relative path to outputPath.
+      // Example:
+      //   URL: /complex/foo.js  => outputPath/complex/foo.js
+      //   URL: /complex/        => outputPath/complex/index.html (or the configured index file)
       filename = path.join(
         outputPath,
         pathname.slice(publicPathPathname.length),
+        index || "",
       );
 
       try {
diff --git a/test/middleware.test.js b/test/middleware.test.js
index 3c0836a8a..63cb8e90b 100644
--- a/test/middleware.test.js
+++ b/test/middleware.test.js
@@ -1736,6 +1736,10 @@ describe.each([
                 value: "noextension",
                 code: 200,
               },
+              {
+                value: "noextension/",
+                code: 404,
+              },
             ],
           },
           {
@@ -1780,6 +1784,11 @@ describe.each([
                 contentType: "text/plain; charset=utf-8",
                 code: 200,
               },
+              {
+                value: "windows%202.txt/",
+                contentType: get404ContentTypeHeader(name),
+                code: 404,
+              },
             ],
           },
           {
@@ -1945,7 +1954,7 @@ describe.each([
 
                   expect(response.statusCode).toEqual(code);
 
-                  if (data) {
+                  if (data && code !== 404) {
                     expect(response.headers["content-length"]).toEqual(
                       String(data.length),
                     );
@@ -5100,6 +5109,15 @@ describe.each([
           );
         });
 
+        it('should return the "404" code for the "GET" request to the  "index.html" file', async () => {
+          const response = await req.get("/index.html/");
+
+          expect(response.statusCode).toBe(404);
+          expect(response.headers["content-type"]).toEqual(
+            get404ContentTypeHeader(name),
+          );
+        });
+
         it('should return the "200" code for the "GET" request to the "index.html" file', async () => {
           const response = await req.get("/index.html");
 
@@ -5169,10 +5187,22 @@ describe.each([
           instance.context.outputFileSystem.mkdirSync(outputPath, {
             recursive: true,
           });
+
+          instance.context.outputFileSystem.mkdirSync(
+            path.resolve(outputPath, "slug"),
+            {
+              recursive: true,
+            },
+          );
           instance.context.outputFileSystem.writeFileSync(
             path.resolve(outputPath, "default.html"),
             "hello",
           );
+
+          instance.context.outputFileSystem.writeFileSync(
+            path.resolve(outputPath, "slug", "default.html"),
+            "hello",
+          );
         });
 
         afterAll(async () => {
@@ -5187,6 +5217,33 @@ describe.each([
             "text/html; charset=utf-8",
           );
         });
+
+        it('should return the "200" code for the "GET" request to the "/slug/" path', async () => {
+          const response = await req.get("/slug/");
+
+          expect(response.statusCode).toBe(200);
+          expect(response.headers["content-type"]).toBe(
+            "text/html; charset=utf-8",
+          );
+        });
+
+        it('should return the "200" code for the "GET" request to the "/slug" path', async () => {
+          const response = await req.get("/slug");
+
+          expect(response.statusCode).toBe(200);
+          expect(response.headers["content-type"]).toBe(
+            "text/html; charset=utf-8",
+          );
+        });
+
+        it('should return the "404" code for the "GET" request with a non-existent file', async () => {
+          const response = await req.get("/default.html/");
+
+          expect(response.statusCode).toBe(404);
+          expect(response.headers["content-type"]).toBe(
+            get404ContentTypeHeader(name),
+          );
+        });
       });
 
       describe('should work with "string" value with a custom extension', () => {