diff --git a/akka-http-core/src/main/scala/akka/http/scaladsl/model/headers/headers.scala b/akka-http-core/src/main/scala/akka/http/scaladsl/model/headers/headers.scala
index d6ae928e316..ffd1c35a4d8 100644
--- a/akka-http-core/src/main/scala/akka/http/scaladsl/model/headers/headers.scala
+++ b/akka-http-core/src/main/scala/akka/http/scaladsl/model/headers/headers.scala
@@ -766,7 +766,7 @@ private[http] object `Sec-WebSocket-Extensions` extends ModeledCompanion[`Sec-We
  */
 @InternalApi
 private[http] final case class `Sec-WebSocket-Extensions`(extensions: immutable.Seq[WebSocketExtension])
-  extends ResponseHeader {
+  extends RequestResponseHeader {
   require(extensions.nonEmpty, "Sec-WebSocket-Extensions.extensions must not be empty")
   import `Sec-WebSocket-Extensions`.extensionsRenderer
   protected[http] def renderValue[R <: Rendering](r: R): r.type = r ~~ extensions
diff --git a/akka-http-core/src/test/scala/akka/http/scaladsl/model/headers/HeaderSpec.scala b/akka-http-core/src/test/scala/akka/http/scaladsl/model/headers/HeaderSpec.scala
index 17972833004..6b8b84a3c0d 100644
--- a/akka-http-core/src/test/scala/akka/http/scaladsl/model/headers/HeaderSpec.scala
+++ b/akka-http-core/src/test/scala/akka/http/scaladsl/model/headers/HeaderSpec.scala
@@ -7,7 +7,8 @@ package akka.http.scaladsl.model.headers
 import akka.http.impl.util._
 import org.scalatest._
 import java.net.InetAddress
-import akka.http.scaladsl.model._
+
+import akka.http.scaladsl.model.{ headers, _ }
 
 class HeaderSpec extends FreeSpec with Matchers {
   "ModeledCompanion should" - {
@@ -132,6 +133,7 @@ class HeaderSpec extends FreeSpec with Matchers {
         `Proxy-Authorization`(BasicHttpCredentials("johan", "correcthorsebatterystaple")),
         Range(RangeUnits.Bytes, Vector(ByteRange(1, 1024))),
         Referer(Uri("http://example.com/")),
+        `Sec-WebSocket-Extensions`(Vector(WebSocketExtension("permessage-deflate"), WebSocketExtension("client_max_window_bits"))),
         `Sec-WebSocket-Protocol`(Vector("chat", "superchat")),
         `Sec-WebSocket-Key`("dGhlIHNhbXBsZSBub25jZQ"),
         `Sec-WebSocket-Version`(Vector(13)),