diff --git a/crates/border-wars/src/camera.rs b/crates/border-wars/src/camera.rs
index 067da21..6c2b50b 100644
--- a/crates/border-wars/src/camera.rs
+++ b/crates/border-wars/src/camera.rs
@@ -114,7 +114,7 @@ fn scale_system(
                 return;
             }
 
-            let future_scale = event.y.mul_add(scale_speed.0, projection.scale);
+            let future_scale = event.y.mul_add(-scale_speed.0, projection.scale);
             if min_scale.0 < future_scale && future_scale < max_scale.0 {
                 projection.scale = future_scale;
             }