diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3ac7ab93..ab5a1ea4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@
   ```
 
   SQLPage now keeps the variable value, producing `https://api.example.com/john.doe` as expected.
+- A request that resolves to a directory now returns a 404 page. Directory names that contain a dot are routed to the static file handler, which used to fail with a server error instead.
 - A `content_security_policy` that does not contain `'nonce-{NONCE}'` is now sent as written, instead of being silently dropped and leaving the response with no `Content-Security-Policy` header at all. Setting the option to the empty string still disables the header, as documented.
 
 ## v0.46
diff --git a/src/filesystem.rs b/src/filesystem.rs
index 4b29483f..71c8fba7 100644
--- a/src/filesystem.rs
+++ b/src/filesystem.rs
@@ -90,8 +90,7 @@ impl FileSystem {
                     .await
             }
             (Err(e), _) => {
-                let status = io_error_status(&e)
-                    .unwrap_or(actix_web::http::StatusCode::INTERNAL_SERVER_ERROR);
+                let status = io_error_status(&local_path, &e).await;
                 Err(e).with_status(status).with_context(|| {
                     format!("Unable to read local file metadata for {}", path.display())
                 })
@@ -146,12 +145,8 @@ impl FileSystem {
                 // no local file, try the database
                 db_fs.read_file(app_state, path.as_ref()).await
             }
-            (Err(e), None) if is_path_missing_error(&e) => Err(e)
-                .with_status(actix_web::http::StatusCode::NOT_FOUND)
-                .with_context(|| format!("Unable to read local file {}", path.display())),
             (Err(e), _) => {
-                let status = io_error_status(&e)
-                    .unwrap_or(actix_web::http::StatusCode::INTERNAL_SERVER_ERROR);
+                let status = io_error_status(&local_path, &e).await;
                 Err(e)
                     .with_status(status)
                     .with_context(|| format!("Unable to read local file {}", path.display()))
@@ -188,12 +183,11 @@ impl FileSystem {
     ) -> anyhow::Result<bool> {
         let path = access.path();
         let safe_path = self.safe_local_path(app_state, access);
-        let local_exists = match tokio::fs::try_exists(safe_path).await {
+        let local_exists = match tokio::fs::try_exists(&safe_path).await {
             Ok(exists) => exists,
             Err(e) if is_path_missing_error(&e) => false,
             Err(e) => {
-                let status = io_error_status(&e)
-                    .unwrap_or(actix_web::http::StatusCode::INTERNAL_SERVER_ERROR);
+                let status = io_error_status(&safe_path, &e).await;
                 return Err(e).with_status(status).with_context(|| {
                     format!("Unable to check if {} exists locally", path.display())
                 });
@@ -252,16 +246,27 @@ fn is_path_missing_error(error: &std::io::Error) -> bool {
     matches!(error.kind(), ErrorKind::NotFound | ErrorKind::NotADirectory)
 }
 
-fn io_error_status(error: &std::io::Error) -> Option<actix_web::http::StatusCode> {
+async fn io_error_status(local_path: &Path, error: &std::io::Error) -> actix_web::http::StatusCode {
     match error.kind() {
-        ErrorKind::NotFound | ErrorKind::NotADirectory => {
-            Some(actix_web::http::StatusCode::NOT_FOUND)
+        ErrorKind::NotFound | ErrorKind::NotADirectory => actix_web::http::StatusCode::NOT_FOUND,
+        // Reading a directory reports IsADirectory on unix but PermissionDenied on
+        // windows, so the path itself has to be inspected to tell the two apart.
+        ErrorKind::IsADirectory | ErrorKind::PermissionDenied
+            if is_local_directory(local_path).await =>
+        {
+            actix_web::http::StatusCode::NOT_FOUND
         }
-        ErrorKind::PermissionDenied => Some(actix_web::http::StatusCode::FORBIDDEN),
-        _ => None,
+        ErrorKind::PermissionDenied => actix_web::http::StatusCode::FORBIDDEN,
+        _ => actix_web::http::StatusCode::INTERNAL_SERVER_ERROR,
     }
 }
 
+async fn is_local_directory(path: &Path) -> bool {
+    tokio::fs::metadata(path)
+        .await
+        .is_ok_and(|metadata| metadata.is_dir())
+}
+
 async fn file_modified_since_local(path: &Path, since: DateTime<Utc>) -> tokio::io::Result<bool> {
     tokio::fs::metadata(path)
         .await
@@ -506,3 +511,25 @@ async fn test_sql_file_read_utf8() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+#[actix_web::test]
+async fn test_local_file_modification_time() -> anyhow::Result<()> {
+    let config = crate::app_config::tests::test_config();
+    let state = AppState::init(&config).await?;
+    let fs = FileSystem::init(".", &state.db).await;
+    let committed_file = || FileAccess::unprivileged("tests/it_works.txt".as_ref());
+
+    assert!(
+        fs.modified_since(&state, committed_file()?, DateTime::UNIX_EPOCH)
+            .await?
+    );
+    assert!(
+        !fs.modified_since(
+            &state,
+            committed_file()?,
+            Utc::now() + chrono::Duration::hours(1)
+        )
+        .await?
+    );
+    Ok(())
+}
diff --git a/tests/errors/is_a_directory.d/contents.txt b/tests/errors/is_a_directory.d/contents.txt
new file mode 100644
index 00000000..d3d9f263
--- /dev/null
+++ b/tests/errors/is_a_directory.d/contents.txt
@@ -0,0 +1 @@
+not directly servable
diff --git a/tests/errors/mod.rs b/tests/errors/mod.rs
index fc66d22b..a6bfe55a 100644
--- a/tests/errors/mod.rs
+++ b/tests/errors/mod.rs
@@ -173,3 +173,13 @@ async fn test_default_404_when_request_path_descends_into_file() {
     assert!(body.contains("The page you were looking for does not exist"));
     assert!(!body.contains("error"));
 }
+
+#[actix_web::test]
+async fn test_requesting_a_directory_is_not_found() {
+    let resp_result = req_path("/tests/errors/is_a_directory.d").await;
+    let status = match resp_result {
+        Ok(resp) => resp.status(),
+        Err(e) => e.as_response_error().status_code(),
+    };
+    assert_eq!(status, StatusCode::NOT_FOUND);
+}