diff --git a/packages/next-swc/crates/next-core/src/app_structure.rs b/packages/next-swc/crates/next-core/src/app_structure.rs
index 5f59531b3950..2bd7c634ec77 100644
--- a/packages/next-swc/crates/next-core/src/app_structure.rs
+++ b/packages/next-swc/crates/next-core/src/app_structure.rs
@@ -373,6 +373,7 @@ async fn add_app_page(
     key: String,
     loader_tree: LoaderTreeVc,
 ) -> Result<()> {
+    let key = get_underscore_normalized_path(&key);
     match result.entry(key) {
         Entry::Occupied(mut e) => {
             let value = e.get_mut();
@@ -401,6 +402,7 @@ async fn add_app_route(
     key: String,
     path: FileSystemPathVc,
 ) -> Result<()> {
+    let key = get_underscore_normalized_path(&key);
     match result.entry(key) {
         Entry::Occupied(mut e) => {
             DirectoryTreeIssue {
@@ -442,6 +444,11 @@ async fn directory_tree_to_entrypoints_internal(
 ) -> Result<EntrypointsVc> {
     let mut result = IndexMap::new();
 
+    // appDir ignores paths starting with an underscore
+    if directory_name.starts_with('_') {
+        return Ok(Entrypoints(result).cell());
+    }
+
     let directory_tree = &*directory_tree.await?;
 
     let subdirectories = &directory_tree.subdirectories;
@@ -467,7 +474,7 @@ async fn directory_tree_to_entrypoints_internal(
                 .cell()
             } else {
                 LoaderTree {
-                    segment: directory_name.to_string(),
+                    segment: get_underscore_normalized_path(directory_name),
                     parallel_routes: indexmap! {
                         "children".to_string() => LoaderTree {
                             segment: "__PAGE__".to_string(),
@@ -506,7 +513,7 @@ async fn directory_tree_to_entrypoints_internal(
                 .cell()
             } else {
                 LoaderTree {
-                    segment: directory_name.to_string(),
+                    segment: get_underscore_normalized_path(directory_name),
                     parallel_routes: indexmap! {
                         "children".to_string() => LoaderTree {
                             segment: "__DEFAULT__".to_string(),
@@ -556,7 +563,7 @@ async fn directory_tree_to_entrypoints_internal(
                     } else {
                         let key = parallel_route_key.unwrap_or("children").to_string();
                         let child_loader_tree = LoaderTree {
-                            segment: directory_name.to_string(),
+                            segment: get_underscore_normalized_path(directory_name),
                             parallel_routes: indexmap! {
                                 key => loader_tree,
                             },
@@ -576,6 +583,12 @@ async fn directory_tree_to_entrypoints_internal(
     Ok(EntrypointsVc::cell(result))
 }
 
+/// ref: https://github.com/vercel/next.js/blob/c390c1662bc79e12cf7c037dcb382ef5ead6e492/packages/next/src/build/entries.ts#L119
+/// if path contains %5F, replace it with _.
+fn get_underscore_normalized_path(path: &str) -> String {
+    path.replace("%5F", "_")
+}
+
 #[turbo_tasks::value(shared)]
 struct DirectoryTreeIssue {
     pub severity: IssueSeverityVc,