diff --git a/pkgs/maps/main.fnl b/pkgs/maps/main.fnl
index 09e7945..83d45c2 100644
--- a/pkgs/maps/main.fnl
+++ b/pkgs/maps/main.fnl
@@ -180,7 +180,7 @@ label.readout {
 
 (var map-surface nil)
 
-(fn cairo-the-map [window]
+(fn draw-onto-map-surface [surface]
   (let [{ : lat : lon : zoom } app-state
         { : num-tiles-x : num-tiles-y &as bounds } (map-bounds lat lon zoom)
         road-width 14
@@ -192,13 +192,8 @@ label.readout {
                                       #(set map-surface nil)
                                       ))))
 
-    (let [map-surface
-          (window:create_similar_surface
-           cairo.Content.COLOR
-           (* tile-size (+ 1 num-tiles-x))
-           (* tile-size (+ 1 num-tiles-y)))
-          seen-road-names {}
-          g (cairo.Context.create map-surface)]
+    (let [seen-road-names {}
+          g (cairo.Context.create surface)]
 
       (g:set_source_rgb 0.7 0.8 0.8)
       (g:rectangle 0 0 (* tile-size num-tiles-x) (* tile-size num-tiles-y))
@@ -233,18 +228,23 @@ label.readout {
                 (g:fill)
                 (g:restore)))))
 
-      map-surface)))
+      surface)))
 
 
 (fn on-osm-draw [widget g]
-  (when (not map-surface)
-    (let [window (widget:get_window)]
-      (set map-surface (cairo-the-map window))))
-
   (let [(tile-x tile-y) (tiles.latlon->tile app-state.lat app-state.lon app-state.zoom)
         bounds (map-bounds-tile tile-x tile-y)
         offset-x (- (* tile-size (- tile-x bounds.min.x)) (/ map-width 2))
         offset-y (- (* tile-size (- tile-y bounds.min.y)) (/ map-height 2))]
+    (when (not map-surface)
+      (let [window (widget:get_window)]
+        (set map-surface
+             (doto
+                 (window:create_similar_surface
+                  cairo.Content.COLOR
+                  (* tile-size bounds.num-tiles-x)
+                  (* tile-size bounds.num-tiles-y))
+               draw-onto-map-surface))))
 
     (g:set_source_surface map-surface (- offset-x) (- offset-y))
     (g:set_operator cairo.Operator.SOURCE)