diff --git a/sub_crates/backend/src/hash.rs b/sub_crates/backend/src/hash.rs
index 9607455..c11fadf 100644
--- a/sub_crates/backend/src/hash.rs
+++ b/sub_crates/backend/src/hash.rs
@@ -121,38 +121,31 @@ fn add_buffer_to_state(state: &mut [u64; 4], buffer: &[u8]) {
 /// The main mix function.  Mixes the passed hash state.
 ///
 /// Inspired by Skein 1.3, and using its MIX function.
-///
-/// The mix rotation constants are:
-/// - 40 50
-/// - 27 21
-///
-/// They were selected by an exhaustive search of the four-constant
-/// space, selecting for the best single-bit diffusion at a small
-/// number of rounds.
-///
-/// The permute table is:
-/// - Indices: 0 1 2 3
-/// - Become:  0 1 3 2
 #[inline(always)]
 fn mix_state(state: &mut [u64; 4], rounds: usize) {
-    for _ in 0..rounds {
-        // MIX function.
-        state[0] = state[0].wrapping_add(state[2]);
-        state[2] = state[2].rotate_left(40) ^ state[0];
-        state[1] = state[1].wrapping_add(state[3]);
-        state[3] = state[3].rotate_left(50) ^ state[1];
-
-        // Permute.
-        state.swap(2, 3);
+    const ROTATIONS: &[[u32; 4]] = &[
+        [40, 50, 27, 21],
+        [40, 50, 27, 21],
+        [40, 50, 27, 21],
+        [40, 50, 27, 21],
+    ];
+    for round in 0..rounds {
+        let rot = ROTATIONS[round % ROTATIONS.len()];
 
         // MIX function.
         state[0] = state[0].wrapping_add(state[2]);
-        state[2] = state[2].rotate_left(27) ^ state[0];
+        state[2] = state[2].rotate_left(rot[0]) ^ state[0];
         state[1] = state[1].wrapping_add(state[3]);
-        state[3] = state[3].rotate_left(21) ^ state[1];
+        state[3] = state[3].rotate_left(rot[1]) ^ state[1];
 
-        // Permute.
-        state.swap(2, 3);
+        // We flip the indices we use below, as if we did
+        // a [0 1 2 3] -> [0 1 3 2] permutation.
+
+        // MIX function.
+        state[0] = state[0].wrapping_add(state[3]);
+        state[3] = state[3].rotate_left(rot[2]) ^ state[0];
+        state[1] = state[1].wrapping_add(state[2]);
+        state[2] = state[2].rotate_left(rot[3]) ^ state[1];
     }
 }