diff --git a/src/seismic_hazard_forecasting.py b/src/seismic_hazard_forecasting.py
index 5e415cd..0c48502 100644
--- a/src/seismic_hazard_forecasting.py
+++ b/src/seismic_hazard_forecasting.py
@@ -241,6 +241,9 @@ verbose: {verbose}")
         grid_y_max = int(ceil(y_max / grid_dim) * grid_dim)
         grid_y_min = int(floor(y_min / grid_dim) * grid_dim)
 
+        grid_lat_max, grid_lon_max = utm.to_latlon(grid_x_max, grid_y_max, utm_zone_number, utm_zone_letter)
+        grid_lat_min, grid_lon_min = utm.to_latlon(grid_x_min, grid_y_min, utm_zone_number, utm_zone_letter)
+
         # rectangular grid
         nx = int((grid_x_max - grid_x_min) / grid_dim) + 1
         ny = int((grid_y_max - grid_y_min) / grid_dim) + 1
@@ -503,7 +506,7 @@ verbose: {verbose}")
 
             # Embed geographic bounding box into the SVG
             map_bounds = dict(zip(("south", "west", "north", "east"),
-                            map(float, (lat.min(), lon.min(), lat.max(), lon.max()))))
+                            map(float, (grid_lat_min, grid_lon_min, grid_lat_max, grid_lon_max))))
             tree = ET.parse(overlay_filename)
             tree.getroot().set("data-map-bounds", json.dumps(map_bounds))
             tree.write(overlay_filename, encoding="utf-8", xml_declaration=True)