diff --git a/physics.jai b/physics.jai
index 238e373..87164b0 100644
--- a/physics.jai
+++ b/physics.jai
@@ -267,7 +267,7 @@ main :: () {
                     }
 
                     // gravity
-                    it.force.y += -9.81;
+                    it.force.y += -9.81 * it.shape.mass;
 
                     if !it.static
                     {