diff --git a/pkgs/maps/main.fnl b/pkgs/maps/main.fnl
index 57987ae..5715416 100644
--- a/pkgs/maps/main.fnl
+++ b/pkgs/maps/main.fnl
@@ -33,8 +33,8 @@ label.readout {
          (os.difftime (os.time localt) (os.time utct))))
 
 
-(local map-width 720)
-(local map-height 800)
+(local viewport-width 720)
+(local viewport-height 800)
 (local tile-size 256)
 
 (fn styles []
@@ -49,8 +49,8 @@ label.readout {
 (local window (Gtk.Window {
                            :title "Map"
                            :name "toplevel"
-                           :default_width map-width
-                           :default_height map-height
+                           :default_width viewport-width
+                           :default_height viewport-height
 
                            :on_destroy Gtk.main_quit
                            }))
@@ -76,10 +76,10 @@ label.readout {
 
 
 (fn map-bounds-tile [tile-x tile-y]
-  (let [min-tile-x (math.floor (- tile-x (/ map-width tile-size 2)))
-        max-tile-x (math.floor (+ tile-x (/ map-width tile-size 2)))
-        min-tile-y (math.floor (- tile-y (/ map-height tile-size 2)))
-        max-tile-y (math.floor (+ tile-y (/ map-height tile-size 2)))
+  (let [min-tile-x (math.floor (- tile-x (/ viewport-width tile-size 2)))
+        max-tile-x (math.floor (+ tile-x (/ viewport-width tile-size 2)))
+        min-tile-y (math.floor (- tile-y (/ viewport-height tile-size 2)))
+        max-tile-y (math.floor (+ tile-y (/ viewport-height tile-size 2)))
         num-tiles-x (+ 1 (- max-tile-x min-tile-x))
         num-tiles-y (+ 1 (- max-tile-y min-tile-y))]
 
@@ -100,7 +100,7 @@ label.readout {
 (let [bounds (map-bounds-tile 65539.5 45014.5)]
   ;; tile 65539, 45014 is centred on screen. left of it there is space
   ;; for one tile and right of it likewise.
-  ;; vertical space for other tiles is (/ (- map-height tile-size) 256)
+  ;; vertical space for other tiles is (/ (- viewport-height tile-size) 256)
   ;;  => 2.125 tiles, shared equally to top and bottom therefore
   ;; 1.0625 tiles above and 1.0625 tiles below
 
@@ -240,8 +240,8 @@ label.readout {
 (fn on-osm-draw [widget g]
   (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))]
+        offset-x (- (* tile-size (- tile-x bounds.min.x)) (/ viewport-width 2))
+        offset-y (- (* tile-size (- tile-y bounds.min.y)) (/ viewport-height 2))]
 
     (when (not map-surface)
       (let [window (widget:get_window)]
@@ -255,7 +255,7 @@ label.readout {
 
     (g:set_source_surface map-surface (- offset-x) (- offset-y))
     (g:set_operator cairo.Operator.SOURCE)
-    (g:rectangle 0 0 map-width map-height)
+    (g:rectangle 0 0 viewport-width viewport-height)
     (g:fill)))
 
 
@@ -268,7 +268,7 @@ label.readout {
   (register-widget
    :osm
    (Gtk.DrawingArea {
-                     :width map-width :height map-height
+                     :width viewport-width :height viewport-height
                      :on_draw on-osm-draw
                      })))