diff --git a/akka-http-core/src/main/scala/akka/http/model/Uri.scala b/akka-http-core/src/main/scala/akka/http/model/Uri.scala
index db7d1ee2ad..6a3dd47c68 100644
--- a/akka-http-core/src/main/scala/akka/http/model/Uri.scala
+++ b/akka-http-core/src/main/scala/akka/http/model/Uri.scala
@@ -809,8 +809,9 @@ object UriRendering {
         renderPath(encode(r, head, charset, keep), tail, charset)
     }
 
-  def renderQuery[R <: Rendering](r: R, query: Query, charset: Charset): r.type = {
-    def enc(s: String): Unit = encode(r, s, charset, `strict-query-char-np`, replaceSpaces = true)
+  def renderQuery[R <: Rendering](r: R, query: Query, charset: Charset,
+                                  keep: CharPredicate = `strict-query-char-np`): r.type = {
+    def enc(s: String): Unit = encode(r, s, charset, keep, replaceSpaces = true)
     @tailrec def append(q: Query): r.type =
       q match {
         case Query.Empty ⇒ r
diff --git a/akka-http-tests/src/test/scala/akka/http/FormDataSpec.scala b/akka-http-tests/src/test/scala/akka/http/FormDataSpec.scala
new file mode 100644
index 0000000000..81b2efb471
--- /dev/null
+++ b/akka-http-tests/src/test/scala/akka/http/FormDataSpec.scala
@@ -0,0 +1,42 @@
+/**
+ * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
+ */
+
+package akka.http
+
+import scala.concurrent.duration._
+import org.scalatest.{ BeforeAndAfterAll, Matchers, WordSpec }
+import org.scalatest.concurrent.ScalaFutures
+import akka.actor.ActorSystem
+import akka.stream.FlowMaterializer
+import akka.http.unmarshalling.Unmarshal
+import akka.http.marshalling.Marshal
+import akka.http.model._
+
+class FormDataSpec extends WordSpec with Matchers with ScalaFutures with BeforeAndAfterAll {
+  implicit val system = ActorSystem(getClass.getSimpleName)
+  implicit val materializer = FlowMaterializer()
+  import system.dispatcher
+
+  val formData = FormData(Map("surname" -> "Smith", "age" -> "42"))
+
+  "The FormData infrastructure" should {
+    "properly round-trip the fields of www-urlencoded forms" in {
+      Marshal(formData).to[HttpEntity]
+        .flatMap(Unmarshal(_).to[FormData]).futureValue shouldEqual formData
+    }
+
+    "properly marshal www-urlencoded forms containing special chars" in {
+      Marshal(FormData(Map("name" -> "Smith&Wesson"))).to[HttpEntity]
+        .flatMap(Unmarshal(_).to[String]).futureValue shouldEqual "name=Smith%26Wesson"
+
+      Marshal(FormData(Map("name" -> "Smith+Wesson; hopefully!"))).to[HttpEntity]
+        .flatMap(Unmarshal(_).to[String]).futureValue shouldEqual "name=Smith%2BWesson%3B+hopefully%21"
+    }
+  }
+
+  override def afterAll() = {
+    system.shutdown()
+    system.awaitTermination(10.seconds)
+  }
+}
diff --git a/akka-http/src/main/scala/akka/http/marshalling/PredefinedToEntityMarshallers.scala b/akka-http/src/main/scala/akka/http/marshalling/PredefinedToEntityMarshallers.scala
index 0472ab7ee3..7b6849336d 100644
--- a/akka-http/src/main/scala/akka/http/marshalling/PredefinedToEntityMarshallers.scala
+++ b/akka-http/src/main/scala/akka/http/marshalling/PredefinedToEntityMarshallers.scala
@@ -7,6 +7,7 @@ package akka.http.marshalling
 import java.nio.CharBuffer
 import scala.concurrent.ExecutionContext
 import scala.xml.NodeSeq
+import akka.http.model.parser.CharacterClasses
 import akka.http.model.MediaTypes._
 import akka.http.model._
 import akka.http.util.{ FastFuture, StringRendering }
@@ -57,7 +58,8 @@ trait PredefinedToEntityMarshallers extends MultipartMarshallers {
 
   implicit val FormDataMarshaller: ToEntityMarshaller[FormData] =
     Marshaller.withOpenCharset(`application/x-www-form-urlencoded`) { (formData, charset) ⇒
-      val string = UriRendering.renderQuery(new StringRendering, Uri.Query(formData.fields: _*), charset.nioCharset).get
+      val query = Uri.Query(formData.fields: _*)
+      val string = UriRendering.renderQuery(new StringRendering, query, charset.nioCharset, CharacterClasses.unreserved).get
       HttpEntity(ContentType(`application/x-www-form-urlencoded`, charset), string)
     }