diff --git a/kernel/src/main/scala-2.12/cats/kernel/compat/HashCompat.scala b/kernel/src/main/scala-2.12/cats/kernel/compat/HashCompat.scala
index 5f21b95f99f..86bc9ddcbf3 100644
--- a/kernel/src/main/scala-2.12/cats/kernel/compat/HashCompat.scala
+++ b/kernel/src/main/scala-2.12/cats/kernel/compat/HashCompat.scala
@@ -45,7 +45,7 @@ package compat
 
 private[kernel] class HashCompat {
   // Adapted from scala.util.hashing.MurmurHash#productHash.
-  private[kernel] def product1HashWithPrefix(_1Hash: Int, prefix: String): Int = {
+  private[kernel] def product1HashWithPrefix(_1Hash: Int, @unused prefix: String): Int = {
     import scala.util.hashing.MurmurHash3._
     var h = productSeed
     h = mix(h, _1Hash)
@@ -53,7 +53,7 @@ private[kernel] class HashCompat {
   }
 
   // Adapted from scala.util.hashing.MurmurHash#productHash.
-  private[cats] def product2HashWithPrefix(_1Hash: Int, _2Hash: Int, prefix: String): Int = {
+  private[cats] def product2HashWithPrefix(_1Hash: Int, _2Hash: Int, @unused prefix: String): Int = {
     import scala.util.hashing.MurmurHash3._
     var h = productSeed
     h = mix(h, _1Hash)
diff --git a/kernel/src/main/scala/cats/kernel/instances/MapInstances.scala b/kernel/src/main/scala/cats/kernel/instances/MapInstances.scala
index f55ec241b55..8cc84e4a8ff 100644
--- a/kernel/src/main/scala/cats/kernel/instances/MapInstances.scala
+++ b/kernel/src/main/scala/cats/kernel/instances/MapInstances.scala
@@ -42,12 +42,14 @@
 package cats.kernel
 package instances
 
+import cats.kernel.compat.scalaVersionSpecific._
+import cats.kernel.compat.unused
+
 import scala.collection.mutable
-import compat.scalaVersionSpecific._
 
 @suppressUnusedImportWarningForScalaVersionSpecific
 trait MapInstances extends MapInstances1 {
-  implicit def catsKernelStdHashForMap[K: Hash, V: Hash]: Hash[Map[K, V]] =
+  implicit def catsKernelStdHashForMap[K, V](implicit @unused K: Hash[K], V: Hash[V]): Hash[Map[K, V]] =
     new MapHash[K, V]
 
   implicit def catsKernelStdCommutativeMonoidForMap[K, V: CommutativeSemigroup]: CommutativeMonoid[Map[K, V]] =