diff --git a/core/src/main/scala/cats/data/WriterT.scala b/core/src/main/scala/cats/data/WriterT.scala
index c9acca8505..a31269e795 100644
--- a/core/src/main/scala/cats/data/WriterT.scala
+++ b/core/src/main/scala/cats/data/WriterT.scala
@@ -25,7 +25,7 @@ package data
 import cats.Foldable
 import cats.kernel.CommutativeMonoid
 
-final case class WriterT[F[_], L, V](run: F[(L, V)]) {
+final case class WriterT[F[_], +L, +V](run: F[(L, V)]) {
 
   /**
    * Example: