diff --git a/play-json-generic/src/test/scala/com/evolution/playjson/generic/NestedTypeFormatSpec.scala b/play-json-generic/src/test/scala/com/evolution/playjson/generic/NestedTypeFormatSpec.scala
index 1fd6cff..bbe73b6 100644
--- a/play-json-generic/src/test/scala/com/evolution/playjson/generic/NestedTypeFormatSpec.scala
+++ b/play-json-generic/src/test/scala/com/evolution/playjson/generic/NestedTypeFormatSpec.scala
@@ -5,7 +5,7 @@ import Message._
 
 class NestedTypeFormatSpec extends JsonFormatSpec {
 
-  implicit val messageFormat = {
+  implicit val messageFormat: OFormat[Message] = {
     implicit val noopFormat: OFormat[Noop.type] = new OFormat[Noop.type] {
       def writes(o: Noop.type): JsObject = Json.obj()
       def reads(json: JsValue): JsResult[Message.Noop.type] = JsSuccess(Message.Noop)
diff --git a/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/PlayJsonImplicits.scala b/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/PlayJsonImplicits.scala
index 8d1857a..e2d962d 100644
--- a/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/PlayJsonImplicits.scala
+++ b/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/PlayJsonImplicits.scala
@@ -1,14 +1,14 @@
 package com.evolution.playjson.jsoniter
 
 import com.evolution.playjson.jsoniter.TestDataGenerators.{Address, User}
-import play.api.libs.json.Json
+import play.api.libs.json.{Json, OWrites, Reads}
 
 trait PlayJsonImplicits {
 
-  implicit val e = Json.reads[Address]
-  implicit val f = Json.writes[Address]
+  implicit val e: Reads[Address] = Json.reads[Address]
+  implicit val f: OWrites[Address] = Json.writes[Address]
 
-  implicit val g = Json.reads[User]
-  implicit val h = Json.writes[User]
+  implicit val g: Reads[User] = Json.reads[User]
+  implicit val h: OWrites[User] = Json.writes[User]
 
 }
diff --git a/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/PlayJsonWithJsoniterBackendSpec.scala b/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/PlayJsonWithJsoniterBackendSpec.scala
index 2565310..3a9350d 100644
--- a/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/PlayJsonWithJsoniterBackendSpec.scala
+++ b/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/PlayJsonWithJsoniterBackendSpec.scala
@@ -14,7 +14,7 @@ object PlayJsonWithJsoniterBackendSpec extends org.scalacheck.Properties("PlayJs
 
   implicit def generator: Arbitrary[User] = Arbitrary(genUser)
 
-  property("Write using PlayJson -> Read using Jsoniter") = forAll { user: User =>
+  property("Write using PlayJson -> Read using Jsoniter") = forAll { (user: User) =>
     val jsValue = Json.toJson(user)
     val bts = Json.toBytes(jsValue)
     val actJsValue = PlayJsonJsoniter.deserialize(bts).map(Json.fromJson[User](_))
@@ -23,7 +23,7 @@ object PlayJsonWithJsoniterBackendSpec extends org.scalacheck.Properties("PlayJs
 
   property("Write using PlayJson -> Read using Jsoniter. Batch") = forAll(
     Gen.containerOfN[Vector, User](Size, genUser),
-  ) { batch: Vector[User] =>
+  ) { (batch: Vector[User]) =>
     val bools = batch.map { user =>
       val jsValue = Json.toJson(user)
       val bts = Json.toBytes(jsValue)
@@ -36,7 +36,7 @@ object PlayJsonWithJsoniterBackendSpec extends org.scalacheck.Properties("PlayJs
 
   property("Write using Jsoniter -> Read using Jsoniter. Batch") = forAll(
     Gen.containerOfN[Vector, User](Size, genUser),
-  ) { batch: Vector[User] =>
+  ) { (batch: Vector[User]) =>
     val bools = batch.map { user =>
       val jsValue = Json.toJson(user)
       val bts = PlayJsonJsoniter.serialize(jsValue)
diff --git a/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/RandomJsonArraysSpec.scala b/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/RandomJsonArraysSpec.scala
index 6012488..868ed30 100644
--- a/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/RandomJsonArraysSpec.scala
+++ b/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/RandomJsonArraysSpec.scala
@@ -18,7 +18,7 @@ object RandomJsonArraysSpec extends org.scalacheck.Properties("RandomJsonSpec")
   override def overrideParameters(p: Test.Parameters): Test.Parameters =
     p.withMinSuccessfulTests(Size)
 
-  property("Random json arrays") = forAll { array: value.JsArray =>
+  property("Random json arrays") = forAll { (array: value.JsArray) =>
     val json = array.toString
     val jsValue = Json.parse(json)
     val bts = PlayJsonJsoniter.serialize(jsValue)
diff --git a/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/RandomJsonObjectsSpec.scala b/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/RandomJsonObjectsSpec.scala
index ee05bf2..7ed55d6 100644
--- a/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/RandomJsonObjectsSpec.scala
+++ b/play-json-jsoniter/jvm/src/test/scala-2.13/com/evolution/playjson/jsoniter/RandomJsonObjectsSpec.scala
@@ -18,7 +18,7 @@ object RandomJsonObjectsSpec extends org.scalacheck.Properties("RandomJsonObject
   override def overrideParameters(p: Test.Parameters): Test.Parameters =
     p.withMinSuccessfulTests(Size)
 
-  property("Random json objects") = forAll { obj: value.JsObj =>
+  property("Random json objects") = forAll { (obj: value.JsObj) =>
     val json = obj.toString
     val jsValue = Json.parse(json)
     val bts = PlayJsonJsoniter.serialize(jsValue)
diff --git a/play-json-tools/src/main/scala/com/evolution/playjson/tools/PlayJson27xCompat.scala b/play-json-tools/src/main/scala/com/evolution/playjson/tools/PlayJson27xCompat.scala
index 09e3d06..fbfa246 100644
--- a/play-json-tools/src/main/scala/com/evolution/playjson/tools/PlayJson27xCompat.scala
+++ b/play-json-tools/src/main/scala/com/evolution/playjson/tools/PlayJson27xCompat.scala
@@ -10,7 +10,7 @@ object PlayJson27xCompat {
   implicit def iterableWrites[A, B](implicit ev: B <:< Iterable[A], writes: Writes[A]): Writes[B] = {
     Writes[B] { as =>
       val builder = mutable.ArrayBuilder.make[JsValue]
-      as.foreach { a: A => builder += writes.writes(a) }
+      as.foreach { (a: A) => builder += writes.writes(a) }
       JsArray(builder.result())
     }
   }
diff --git a/play-json-tools/src/main/scala/com/evolution/playjson/tools/PlayJsonHelper.scala b/play-json-tools/src/main/scala/com/evolution/playjson/tools/PlayJsonHelper.scala
index 6201e48..522f162 100644
--- a/play-json-tools/src/main/scala/com/evolution/playjson/tools/PlayJsonHelper.scala
+++ b/play-json-tools/src/main/scala/com/evolution/playjson/tools/PlayJsonHelper.scala
@@ -37,7 +37,7 @@ object PlayJsonHelper {
       readStr orElse readNum
     }
 
-    def writes(o: FiniteDuration) = JsString(o.toCoarsest.toString)
+    def writes(o: FiniteDuration): JsString = JsString(o.toCoarsest.toString)
   }
 
 
@@ -90,7 +90,7 @@ object PlayJsonHelper {
           a <- from(a) map { x => JsSuccess(x) } getOrElse JsError(s"No ${ tag.runtimeClass.getName } found for $a")
         } yield a
 
-        def writes(a: A) = JsString(to(a))
+        def writes(a: A): JsString = JsString(to(a))
       }
     }
   }
@@ -107,7 +107,7 @@ object PlayJsonHelper {
           a <- from(a) map { x => JsSuccess(x) } getOrElse JsError(s"No ${ tag.runtimeClass.getName } found for $a")
         } yield a
 
-        def writes(x: A) = JsNumber(to(x))
+        def writes(x: A): JsNumber = JsNumber(to(x))
       }
     }
   }
@@ -226,7 +226,7 @@ object PlayJsonHelper {
 
       implicit val writesTuple: Writes[(K, V)] = new Writes[(K, V)] {
 
-        def writes(kv: (K, V)) = {
+        def writes(kv: (K, V)): JsObject = {
           val (k, v) = kv
           val json = Json.toJson(v) match {
             case json: JsObject => json
@@ -237,7 +237,7 @@ object PlayJsonHelper {
       }
 
       new Writes[Map[K, V]] {
-        def writes(kvs: Map[K, V]) = {
+        def writes(kvs: Map[K, V]): JsValue = {
           Json.toJson(kvs.toList)
         }
       }
diff --git a/play-json-tools/src/test/scala/com/evolution/playjson/tools/DiscriminatedEitherFormatSpec.scala b/play-json-tools/src/test/scala/com/evolution/playjson/tools/DiscriminatedEitherFormatSpec.scala
index 4bb82b8..41a8100 100644
--- a/play-json-tools/src/test/scala/com/evolution/playjson/tools/DiscriminatedEitherFormatSpec.scala
+++ b/play-json-tools/src/test/scala/com/evolution/playjson/tools/DiscriminatedEitherFormatSpec.scala
@@ -6,7 +6,7 @@ import org.scalatest.matchers.should.Matchers
 import play.api.libs.json._
 
 class DiscriminatedEitherFormatSpec extends AnyFunSuite with Matchers {
-  implicit val eitherFormat = DiscriminatedEitherFormat.eitherFormat("L", "R"): OFormat[Either[String, Int]]
+  implicit val eitherFormat: OFormat[Either[String, Int]] = DiscriminatedEitherFormat.eitherFormat("L", "R"): OFormat[Either[String, Int]]
   val left: Either[String, Int] = Left("foo")
   val right: Either[String, Int] = Right(1)
   val fromEitherJson: JsValue => JsResult[Either[String, Int]] = Json.fromJson[Either[String, Int]](_)
diff --git a/play-json-tools/src/test/scala/com/evolution/playjson/tools/TypeFormatSpec.scala b/play-json-tools/src/test/scala/com/evolution/playjson/tools/TypeFormatSpec.scala
index ca805e4..bba9577 100644
--- a/play-json-tools/src/test/scala/com/evolution/playjson/tools/TypeFormatSpec.scala
+++ b/play-json-tools/src/test/scala/com/evolution/playjson/tools/TypeFormatSpec.scala
@@ -11,7 +11,7 @@ class TypeFormatSpec extends AnyFunSuite with Matchers {
   private val mammalJson = Json.obj("type" -> "Mammal", "legs" -> 4)
   private val slothJson = Json.obj("type" -> "Sloth")
 
-  implicit val animalFormat = new TypeFormat[Animal] {
+  implicit val animalFormat: TypeFormat[Animal] = new TypeFormat[Animal] {
     val mammalFormat = Json.format[Mammal]
     val slothFormat = OFormat.const(Sloth)
 
diff --git a/project/plugins.sbt b/project/plugins.sbt
index 9ddaff2..962da05 100644
--- a/project/plugins.sbt
+++ b/project/plugins.sbt
@@ -6,9 +6,9 @@ addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.2.0")
 
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % scalaJSVersion)
 
-addSbtPlugin("org.scoverage" % "sbt-scoverage" % "2.0.7")
+addSbtPlugin("org.scoverage" % "sbt-scoverage" % "2.0.9")
 
-addSbtPlugin("org.scoverage" % "sbt-coveralls" % "1.3.6")
+addSbtPlugin("org.scoverage" % "sbt-coveralls" % "1.3.11")
 
 addSbtPlugin("com.github.sbt" % "sbt-release" % "1.1.0")