diff --git a/terrainrenderer.go b/terrainrenderer.go
index 9d7be29..c48cb43 100644
--- a/terrainrenderer.go
+++ b/terrainrenderer.go
@@ -85,9 +85,9 @@ func (r *terrainRenderer) Handle(ctx ui.Context, event ui.Event) bool {
 			r.project.update(ctx.Renderer())
 		}
 		if r.hover != nil {
-			if e.Y < 0 {
+			if e.MouseWheel < 0 {
 				r.project.ZoomOut(ctx, r.hover.ToF32())
-			} else {
+			} else if e.MouseWheel > 0 {
 				r.project.ZoomIn(ctx, r.hover.ToF32())
 			}
 		}