diff --git a/src/math.rs b/src/math.rs
index 31bc56f..241759f 100644
--- a/src/math.rs
+++ b/src/math.rs
@@ -1,4 +1,5 @@
 /// Linear interpolation.
+#[inline]
 pub fn lerp(a: f32, b: f32, w: f32) -> f32 {
     assert!(0.0 <= w && w <= 1.0);
     a + (b - a) * w
@@ -7,6 +8,7 @@ pub fn lerp(a: f32, b: f32, w: f32) -> f32 {
 /// Bilinear interpolation.
 /// Expected order of `p` is from a nested `for` loop with the outer loop being `y`.
 /// `w` is expected to be `[wx, wy]`
+#[inline]
 pub fn bi_lerp(p: &[f32], w: &[f32]) -> f32 {
     assert_eq!(p.len(), 4);
     assert_eq!(w.len(), 2);
@@ -17,13 +19,18 @@ pub fn bi_lerp(p: &[f32], w: &[f32]) -> f32 {
 /// Trilinear interpolation.
 /// Expected order of `p` is from a nested `for` loop with the outer loop being `z`.
 /// `w` is expected to be `[wx, wy, wz]`.
+#[inline]
 pub fn tri_lerp(p: &[f32], w: &[f32]) -> f32 {
     assert_eq!(p.len(), 8);
     assert_eq!(w.len(), 3);
 
-    let front = bi_lerp(&[p[0], p[1], p[2], p[3]], &[w[0], w[1]]);
-    let back = bi_lerp(&[p[4], p[5], p[6], p[7]], &[w[0], w[1]]);
-    lerp(front, back, w[2])
+    let c00 = p[0] + (p[1] - p[0]) * w[0];
+    let c10 = p[2] + (p[3] - p[2]) * w[0];
+    let c01 = p[4] + (p[5] - p[4]) * w[0];
+    let c11 = p[6] + (p[7] - p[6]) * w[0];
+    let c0 = c00 + (c10 - c00) * w[1];
+    let c1 = c01 + (c11 - c01) * w[1];
+    c0 + (c1 - c0) * w[2]
 }
 
 /// Maps a 3d index to a 1d index