diff --git a/src/commonMain/kotlin/centre/sciprog/maps/MapViewPoint.kt b/src/commonMain/kotlin/centre/sciprog/maps/MapViewPoint.kt
index f6b02c4..1b27e2d 100644
--- a/src/commonMain/kotlin/centre/sciprog/maps/MapViewPoint.kt
+++ b/src/commonMain/kotlin/centre/sciprog/maps/MapViewPoint.kt
@@ -10,10 +10,13 @@ data class MapViewPoint(
     val focus: GeodeticMapCoordinates,
     val zoom: Double,
 ) {
-    val scaleFactor by lazy { WebMercatorProjection.scaleFactor(zoom.roundToInt()) }
+    val scaleFactor by lazy { WebMercatorProjection.scaleFactor(zoom) }
 }
 
-fun MapViewPoint.move(deltaX: Double, deltaY: Double): MapViewPoint {
+/**
+ *
+ */
+internal fun MapViewPoint.move(deltaX: Double, deltaY: Double): MapViewPoint {
     val newCoordinates = GeodeticMapCoordinates.ofRadians(
         (focus.latitude + deltaY / scaleFactor).coerceIn(
             -MercatorProjection.MAXIMUM_LATITUDE,
diff --git a/src/commonMain/kotlin/centre/sciprog/maps/WebMercatorProjection.kt b/src/commonMain/kotlin/centre/sciprog/maps/WebMercatorProjection.kt
index a05816a..db4882b 100644
--- a/src/commonMain/kotlin/centre/sciprog/maps/WebMercatorProjection.kt
+++ b/src/commonMain/kotlin/centre/sciprog/maps/WebMercatorProjection.kt
@@ -14,10 +14,10 @@ public object WebMercatorProjection  {
     /**
      * Compute radians to projection coordinates ratio for given [zoom] factor
      */
-    public fun scaleFactor(zoom: Int) = 256.0 / 2 / PI * 2.0.pow(zoom)
+    public fun scaleFactor(zoom: Double) = 256.0 / 2 / PI * 2.0.pow(zoom)
 
     public fun toGeodetic(mercator: WebMercatorCoordinates): GeodeticMapCoordinates {
-        val scaleFactor = scaleFactor(mercator.zoom)
+        val scaleFactor = scaleFactor(mercator.zoom.toDouble())
         val longitude = mercator.x / scaleFactor - PI
         val latitude = (atan(exp(PI - mercator.y / scaleFactor)) - PI / 4) * 2
         return GeodeticMapCoordinates.ofRadians(latitude, longitude)
@@ -29,7 +29,7 @@ public object WebMercatorProjection  {
     public fun toMercator(gmc: GeodeticMapCoordinates, zoom: Int): WebMercatorCoordinates {
         require(abs(gmc.latitude) <= MercatorProjection.MAXIMUM_LATITUDE) { "Latitude exceeds the maximum latitude for mercator coordinates" }
 
-        val scaleFactor = scaleFactor(zoom)
+        val scaleFactor = scaleFactor(zoom.toDouble())
         return WebMercatorCoordinates(
             zoom = zoom,
             x = scaleFactor * (gmc.longitude + PI),