diff --git a/src/drawing/tri.rs b/src/drawing/tri.rs
index c7256c5..7aa3493 100644
--- a/src/drawing/tri.rs
+++ b/src/drawing/tri.rs
@@ -21,14 +21,14 @@ impl<const CHANNELS: usize> Image<&mut [u8], CHANNELS> {
         // TODO optimize
         for y in y1.min(y2).min(y3) as u32..y1.max(y2).max(y3) as u32 {
             for x in x1.min(x2).min(x3) as u32..x1.max(x2).max(x3) as u32 {
-                let s = (x1 - x3) * (y as f32 - y3) - (y1 - y2) * (x as f32 - x3);
-                let t = (x2 - x1) * (y as f32 - y1) - (y2 - y1) * (x as f32 - x1);
+                let s = (x1 - x3).mul_add(y as f32 - y3, -(y1 - y2) * (x as f32 - x3));
+                let t = (x2 - x1).mul_add(y as f32 - y1, -(y2 - y1) * (x as f32 - x1));
 
                 if (s < 0.0) != (t < 0.0) && s != 0.0 && t != 0.0 {
                     continue;
                 }
 
-                let d = (x3 - x2) * (y as f32 - y2) - (y3 - y2) * (x as f32 - x2);
+                let d = (x3 - x2).mul_add(y as f32 - y2, -(y3 - y2) * (x as f32 - x2));
                 if (d == 0.0 || (d < 0.0) == (s + t <= 0.0))
                     && x < self.width()
                     && y < self.height()