diff --git a/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/HttpService.scala b/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/HttpService.scala
index a15c4da9..1a53caac 100644
--- a/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/HttpService.scala
+++ b/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/HttpService.scala
@@ -66,7 +66,7 @@ class HttpService(
       (url, jsonBody, params, headers) <- EitherT.fromEither[IO](resolveRequestParts(r.url, r.body, r.params, r.headers, ignoreFromWithHeaders)(scenarioContext))
       resolvedRequest = HttpRequest(r.method, url, jsonBody, params, headers)
       configuredRequest = configureRequest(resolvedRequest, config)
-      resp <- client.runRequest(configuredRequest, requestTimeout)
+      resp <- client.runRequest(configuredRequest, requestTimeout)(circeJsonEncoder, Json.showJson) // TODO remove implicits when removing Scala 2.12
       newSession <- EitherT.fromEither[IO](handleResponse(resp, configuredRequest.show, expectedStatus, extractor)(scenarioContext.session))
     } yield newSession
 
diff --git a/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/Http4sClient.scala b/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/Http4sClient.scala
index 6d4b2617..bf03e19b 100644
--- a/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/Http4sClient.scala
+++ b/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/Http4sClient.scala
@@ -97,12 +97,12 @@ class Http4sClient(
     if (moreParams.isEmpty)
       uri
     else {
-      val allParams = uri.query.pairs.appendedAll(moreParams.iterator.map { case (k, v) => (k, Some(v)) })
+      val allParams = uri.query.pairs ++ moreParams.iterator.map { case (k, v) => (k, Some(v)) }
       val newQuery = Query.fromVector(allParams)
       uri.copy(query = newQuery)
     }
 
-  override def runRequest[A: Show](cReq: HttpRequest[A], t: FiniteDuration)(implicit ee: EntityEncoder[IO, A]): EitherT[IO, CornichonError, HttpResponse] =
+  override def runRequest[A](cReq: HttpRequest[A], t: FiniteDuration)(implicit ee: EntityEncoder[IO, A], sh: Show[A]): EitherT[IO, CornichonError, HttpResponse] =
     parseUri(cReq.url).fold(
       e => EitherT.left[HttpResponse](IO.pure(e)),
       uri => EitherT {
diff --git a/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/HttpClient.scala b/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/HttpClient.scala
index 205b623b..eefce4db 100644
--- a/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/HttpClient.scala
+++ b/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/HttpClient.scala
@@ -11,7 +11,7 @@ import scala.concurrent.duration.FiniteDuration
 
 trait HttpClient {
 
-  def runRequest[A: Show](cReq: HttpRequest[A], t: FiniteDuration)(implicit ee: EntityEncoder[IO, A]): EitherT[IO, CornichonError, HttpResponse]
+  def runRequest[A](cReq: HttpRequest[A], t: FiniteDuration)(implicit ee: EntityEncoder[IO, A], sh: Show[A]): EitherT[IO, CornichonError, HttpResponse]
 
   def openStream(req: HttpStreamedRequest, t: FiniteDuration): IO[Either[CornichonError, HttpResponse]]
 
diff --git a/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/NoOpHttpClient.scala b/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/NoOpHttpClient.scala
index 5f1e3270..2c4f0fd1 100644
--- a/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/NoOpHttpClient.scala
+++ b/cornichon-core/src/main/scala/com/github/agourlay/cornichon/http/client/NoOpHttpClient.scala
@@ -12,7 +12,7 @@ import scala.concurrent.duration.FiniteDuration
 
 class NoOpHttpClient extends HttpClient {
 
-  def runRequest[A: Show](cReq: HttpRequest[A], t: FiniteDuration)(implicit ee: EntityEncoder[IO, A]) =
+  def runRequest[A](cReq: HttpRequest[A], t: FiniteDuration)(implicit ee: EntityEncoder[IO, A], sh: Show[A]) =
     EitherT.apply(IO.pure(HttpResponse(200, Nil, "NoOpBody").asRight))
 
   def openStream(req: HttpStreamedRequest, t: FiniteDuration) =