diff --git a/src/main/scala/uk/ac/soton/ecs/can/core/QuarterRound.scala b/src/main/scala/uk/ac/soton/ecs/can/core/QuarterRound.scala
index 5e1ffbae3fc2ddf8b25ff52231290ba0c9641330..b84740baa9d1e52321e6fcaff1da1cc4439406f3 100644
--- a/src/main/scala/uk/ac/soton/ecs/can/core/QuarterRound.scala
+++ b/src/main/scala/uk/ac/soton/ecs/can/core/QuarterRound.scala
@@ -12,20 +12,20 @@ class QuarterRound extends MultiIOModule {
   private def rotateLeft(v: UInt, b: Int): UInt =
     v(31 - b, 0) ## v(31, 32 - b)
 
-  val a0 = in(0)
-  val b0 = in(1)
-  val c0 = in(2)
-  val d0 = in(3)
-
-  val a1 = a0 + b0
-  val d1 = rotateLeft(d0 ^ a1, 16)
-  val c1 = c0 + d1
-  val b1 = rotateLeft(b0 ^ c1, 12)
-
-  val a2 = a1 + b1
-  val d2 = rotateLeft(d1 ^ a2, 8)
-  val c2 = c1 + d2
-  val b2 = rotateLeft(b1 ^ c2, 7)
+  private val a0 = in(0)
+  private val b0 = in(1)
+  private val c0 = in(2)
+  private val d0 = in(3)
+
+  private val a1 = a0 + b0
+  private val d1 = rotateLeft(d0 ^ a1, 16)
+  private val c1 = c0 + d1
+  private val b1 = rotateLeft(b0 ^ c1, 12)
+
+  private val a2 = a1 + b1
+  private val d2 = rotateLeft(d1 ^ a2, 8)
+  private val c2 = c1 + d2
+  private val b2 = rotateLeft(b1 ^ c2, 7)
 
   out(0) := a2
   out(1) := b2