diff --git a/wezterm-gui/src/termwindow/background.rs b/wezterm-gui/src/termwindow/background.rs
index 3b9e34fcc24..94c6ef3e35f 100644
--- a/wezterm-gui/src/termwindow/background.rs
+++ b/wezterm-gui/src/termwindow/background.rs
@@ -491,7 +491,7 @@ impl crate::TermWindow {
         
         let computed_background_height = match layer.def.height {
             BackgroundSize::Cover => match layer.def.width {
-                BackgroundSize::Dimension(n) => (n.evaluate_as_pixels(h_context) / aspect) as f32,
+                BackgroundSize::Dimension(n) => (n.evaluate_as_pixels(h_context) / aspect).floor(),
                 _ => min_aspect_height,
             }
             _ => min_aspect_height,