diff --git a/crates/ui-egui/src/headless.rs b/crates/ui-egui/src/headless.rs
index e6929269..ac206240 100644
--- a/crates/ui-egui/src/headless.rs
+++ b/crates/ui-egui/src/headless.rs
@@ -1670,7 +1670,8 @@ mod tests {
         let parent_index = dir.to_string_lossy().split(['/', '\\']).filter(|p| !p.is_empty()).count() - 1;
         assert_eq!(h.request("ui.clickWidget", json!({"id": format!("crumb:{parent_index}")}), t)["ok"], true);
         h.settle(SETTLE);
-        assert_eq!(h.app.session.browse.as_ref().unwrap().path, dir.to_string_lossy().replace('\\', "/"));
+        // the same folder, whatever the platform's separators (issue #538)
+        assert_eq!(std::path::Path::new(&h.app.session.browse.as_ref().unwrap().path), dir.as_path());
         let _ = std::fs::remove_dir_all(&dir);
     }
 
diff --git a/crates/ui-egui/src/panels/grid.rs b/crates/ui-egui/src/panels/grid.rs
index 1b6644e0..9c0d6a0f 100644
--- a/crates/ui-egui/src/panels/grid.rs
+++ b/crates/ui-egui/src/panels/grid.rs
@@ -717,10 +717,33 @@ fn folder_header(app: &mut LightcraftApp, ui: &mut egui::Ui, b: &lightcraft_engi
     header.response.rect
 }
 
+/// The folders a breadcrumb shows for `path`: each name with the path that opens it, spelled as
+/// in `path` (its separators, a leading `/` or a UNC `\\server\share`; issue #538). A bare drive
+/// (`C:`) gets its separator back: on its own it means the current folder on that drive.
+pub(crate) fn crumbs(path: &str) -> Vec<(&str, String)> {
+    let mut out = Vec::new();
+    let mut start = 0;
+    for (i, c) in path.char_indices().chain(std::iter::once((path.len(), '/'))) {
+        if c != '/' && c != '\\' {
+            continue;
+        }
+        if let Some(part) = path.get(start..i).filter(|p| !p.is_empty()) {
+            let mut to = path.get(..i).unwrap_or(path).to_string();
+            if out.is_empty() && part.ends_with(':') && to == part {
+                to.push(if path.contains('\\') { '\\' } else { '/' });
+            }
+            out.push((part, to));
+        }
+        start = i + c.len_utf8();
+    }
+    out
+}
+
 fn folder_breadcrumbs(app: &mut LightcraftApp, ui: &mut egui::Ui, path: &str) {
     let t = Tokens::get(ui.ctx());
     ui.spacing_mut().item_spacing.x = 4.0;
-    let parts: Vec<&str> = path.split(['/', '\\']).filter(|p| !p.is_empty()).collect();
+    let crumbs = crumbs(path);
+    let parts: Vec<&str> = crumbs.iter().map(|(name, _)| *name).collect();
     // With all sidebars open even four ellipses and their separators can exceed the row.
     // Prefer the current folder, showing more ancestors as space permits.
     let visible = ((ui.available_width() / 80.0) as usize).clamp(1, 4);
@@ -741,9 +764,10 @@ fn folder_breadcrumbs(app: &mut LightcraftApp, ui: &mut egui::Ui, path: &str) {
             if r.hovered() {
                 ui.ctx().set_cursor_icon(egui::CursorIcon::PointingHand);
             }
-            if r.clicked() {
-                let prefix = if path.starts_with('/') { format!("/{}", parts[..=i].join("/")) } else { parts[..=i].join("/") };
-                let _ = app.run("library.browse", json!({"path": prefix}));
+            if r.clicked()
+                && let Some((_, to)) = crumbs.get(i)
+            {
+                let _ = app.run("library.browse", json!({"path": to}));
             }
             ui.label(egui::RichText::new("›").size(13.0).color(t.text_dim));
         }
diff --git a/crates/ui-egui/src/panels/grid_header_tests.rs b/crates/ui-egui/src/panels/grid_header_tests.rs
index c55bffb5..46399162 100644
--- a/crates/ui-egui/src/panels/grid_header_tests.rs
+++ b/crates/ui-egui/src/panels/grid_header_tests.rs
@@ -2,6 +2,21 @@ use egui::{Rect, vec2};
 
 use crate::{LightcraftApp, Services, headless::HeadlessView, i18n::Locale};
 
+/// Issue #538: a breadcrumb opens its folder spelled as the path is, keeping a UNC share's leading
+/// `\\` and giving a bare drive its root back.
+#[test]
+fn breadcrumbs_open_their_folder_as_spelled() {
+    let to = |path: &str| super::crumbs(path).into_iter().map(|(name, to)| (name.to_string(), to)).collect::<Vec<_>>();
+    let pairs = |v: &[(&str, &str)]| v.iter().map(|(a, b)| (a.to_string(), b.to_string())).collect::<Vec<_>>();
+    assert_eq!(to("/Users/me/Pictures"), pairs(&[("Users", "/Users"), ("me", "/Users/me"), ("Pictures", "/Users/me/Pictures")]));
+    assert_eq!(to(r"C:\Users\me"), pairs(&[("C:", r"C:\"), ("Users", r"C:\Users"), ("me", r"C:\Users\me")]));
+    assert_eq!(to("C:/Users"), pairs(&[("C:", "C:/"), ("Users", "C:/Users")]));
+    assert_eq!(to(r"\\server\share\photos"), pairs(&[("server", r"\\server"), ("share", r"\\server\share"), ("photos", r"\\server\share\photos")]));
+    assert_eq!(to("relative/dir/"), pairs(&[("relative", "relative"), ("dir", "relative/dir")]));
+    assert_eq!(to("/Fotos/día 1/写真"), pairs(&[("Fotos", "/Fotos"), ("día 1", "/Fotos/día 1"), ("写真", "/Fotos/día 1/写真")]));
+    assert!(to("").is_empty() && to("/").is_empty() && to(r"\\").is_empty());
+}
+
 fn text_bounds(shape: &egui::Shape, out: &mut Vec<Rect>) {
     match shape {
         egui::Shape::Text(text) => out.push(text.visual_bounding_rect()),