diff --git a/src/app/file_list.rs b/src/app/file_list.rs
index 2ebc852..ee48961 100644
--- a/src/app/file_list.rs
+++ b/src/app/file_list.rs
@@ -84,8 +84,12 @@ impl App {
                                 ui.painter().hline(
                                     rect.x_range(),
                                     y,
+                                    // `Stroke::new` takes `impl Into<f32>`, which
+                                    // gives an unsuffixed literal no concrete type
+                                    // to infer; suffix it rather than lean on the
+                                    // f32 fallback that rustc is removing.
                                     egui::Stroke::new(
-                                        2.0,
+                                        2.0_f32,
                                         ui.visuals().selection.stroke.color,
                                     ),
                                 );