diff --git a/app/src/main/java/com/mirenkov/ktheightmap/MapCanvas.kt b/app/src/main/java/com/mirenkov/ktheightmap/MapCanvas.kt
index e7ae431..10378c6 100644
--- a/app/src/main/java/com/mirenkov/ktheightmap/MapCanvas.kt
+++ b/app/src/main/java/com/mirenkov/ktheightmap/MapCanvas.kt
@@ -228,7 +228,7 @@ fun MapCanvas(
                     val stepLon = coords[step].first
                     val stepOffsetX = SphereMercator.mercateLon(stepLon.toDouble(), level, -TILE_SIZE.toDouble()).toFloat() - offsetX
                     val stepOffsetY = SphereMercator.mercateLat(stepLat.toDouble(), level, -TILE_SIZE.toDouble()).toFloat() - offsetY
-                    if (stepOffsetX >= 0 && stepOffsetY >= 0 && stepOffsetX < size.width && stepOffsetY < size.height)
+                    if (stepOffsetX >= 0 && stepOffsetY >= 0 && stepOffsetX < size.width && stepOffsetY < size.height && heights[step] > 0u)
                         drawRect(
                             color = if (heights[step] > startHeight) Color.Red else Color.Green,
                             size = Size(8F, 8F),