diff --git a/kitty/shaders.c b/kitty/shaders.c
index 0cdb1101e..9c4dbdd3f 100644
--- a/kitty/shaders.c
+++ b/kitty/shaders.c
@@ -873,7 +873,8 @@ draw_window_number(const UIRenderData *ui) {
     color_type digit_color = colorprofile_to_color_with_fallback(ui->screen->color_profile, ui->screen->color_profile->overridden.highlight_bg, ui->screen->color_profile->configured.highlight_bg, ui->screen->color_profile->overridden.default_fg, ui->screen->color_profile->configured.default_fg);
     color_vec3(graphics_program_layouts[GRAPHICS_ALPHA_MASK_PROGRAM].uniforms.amask_fg, digit_color);
     glUniform4f(graphics_program_layouts[GRAPHICS_ALPHA_MASK_PROGRAM].uniforms.amask_bg_premult, 0.f, 0.f, 0.f, 0.f);
-    save_viewport_using_top_left_origin(letter_x, letter_y, lr.width_px, lr.height_px, ui->screen_height);
+    save_viewport_using_top_left_origin(
+        ui->screen_left + letter_x, ui->screen_top + letter_y, lr.width_px, lr.height_px, ui->full_framebuffer_height);
     draw_graphics(GRAPHICS_ALPHA_MASK_PROGRAM, ird, 0, 1, 1.f);
     restore_viewport();
 #undef lr