diff --git a/akka-http-core/src/main/scala/akka/http/impl/engine/parsing/HttpMessageParser.scala b/akka-http-core/src/main/scala/akka/http/impl/engine/parsing/HttpMessageParser.scala
index 781873cdfb..46c997d238 100644
--- a/akka-http-core/src/main/scala/akka/http/impl/engine/parsing/HttpMessageParser.scala
+++ b/akka-http-core/src/main/scala/akka/http/impl/engine/parsing/HttpMessageParser.scala
@@ -84,6 +84,8 @@ private[http] abstract class HttpMessageParser[Output >: MessageOutput <: Parser
         case NotEnoughDataException ⇒
           // we are missing a try/catch{continue} wrapper somewhere
           throw new IllegalStateException("unexpected NotEnoughDataException", NotEnoughDataException)
+        case IllegalHeaderException(error) ⇒
+          failMessageStart(StatusCodes.BadRequest, error)
       }) match {
         case Trampoline(x) ⇒ run(x)
         case x             ⇒ x
diff --git a/akka-http-core/src/test/scala/akka/http/impl/engine/parsing/RequestParserSpec.scala b/akka-http-core/src/test/scala/akka/http/impl/engine/parsing/RequestParserSpec.scala
index a20c8994b2..17dc6ae6bc 100644
--- a/akka-http-core/src/test/scala/akka/http/impl/engine/parsing/RequestParserSpec.scala
+++ b/akka-http-core/src/test/scala/akka/http/impl/engine/parsing/RequestParserSpec.scala
@@ -175,6 +175,28 @@ class RequestParserSpec extends FreeSpec with Matchers with BeforeAndAfterAll {
           |""" should parseTo(HttpRequest(GET, Uri("http://x//foo").toHttpRequestTargetOriginForm, protocol = `HTTP/1.0`))
         closeAfterResponseCompletion shouldEqual Seq(true)
       }
+
+      "with additional fields in Strict-Transport-Security header" in new Test {
+        """GET /hsts HTTP/1.1
+          |Host: x
+          |Strict-Transport-Security: max-age=1; preload; dummy
+          |
+          |""" should parseTo(HttpRequest(
+          GET,
+          "/hsts",
+          headers = List(Host("x"), `Strict-Transport-Security`(1, None)),
+          protocol = `HTTP/1.1`))
+
+        """GET /hsts HTTP/1.1
+          |Host: x
+          |Strict-Transport-Security: max-age=1; dummy; preload
+          |
+          |""" should parseTo(HttpRequest(
+          GET,
+          "/hsts",
+          headers = List(Host("x"), `Strict-Transport-Security`(1, None)),
+          protocol = `HTTP/1.1`))
+      }
     }
 
     "properly parse a chunked request" - {
@@ -453,6 +475,36 @@ class RequestParserSpec extends FreeSpec with Matchers with BeforeAndAfterAll {
           |
           |""" should parseToError(422: StatusCode, ErrorInfo("TRACE requests must not have an entity"))
       }
+
+      "with additional fields in headers" in new Test {
+        """GET / HTTP/1.1
+          |Host: x; dummy
+          |
+          |""" should parseToError(
+          BadRequest,
+          ErrorInfo("Illegal 'host' header: Invalid input ' ', expected 'EOI', ':', UPPER_ALPHA, lower-reg-name-char or pct-encoded (line 1, column 3)", "x; dummy\n  ^"))
+
+        """GET / HTTP/1.1
+          |Content-length: 3; dummy
+          |
+          |""" should parseToError(
+          BadRequest,
+          ErrorInfo("Illegal `Content-Length` header value"))
+
+        """GET / HTTP/1.1
+          |Connection:keep-alive; dummy
+          |
+          |""" should parseToError(
+          BadRequest,
+          ErrorInfo("Illegal 'connection' header: Invalid input ';', expected tchar, OWS, listSep or 'EOI' (line 1, column 11)", "keep-alive; dummy\n          ^"))
+
+        """GET / HTTP/1.1
+          |Transfer-Encoding: chunked; dummy
+          |
+          |""" should parseToError(
+          BadRequest,
+          ErrorInfo("Illegal 'transfer-encoding' header: Invalid input ';', expected OWS, listSep or 'EOI' (line 1, column 8)", "chunked; dummy\n       ^"))
+      }
     }
   }
 
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 4d3f62733d..b84d0d104b 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
@@ -68,6 +68,12 @@ class HeaderSpec extends FreeSpec with Matchers {
         headers.`Strict-Transport-Security`.parseFromValueString("max-age=30; includeSubDomains") shouldEqual Right(headers.`Strict-Transport-Security`(30, true))
         headers.`Strict-Transport-Security`.parseFromValueString("max-age=30; includeSubDomains; preload") shouldEqual Right(headers.`Strict-Transport-Security`(30, true))
       }
+      "successful parse run with additional values" in {
+        headers.`Strict-Transport-Security`.parseFromValueString("max-age=30; includeSubDomains; preload; dummy") shouldEqual
+          Right(headers.`Strict-Transport-Security`(30, true))
+        headers.`Strict-Transport-Security`.parseFromValueString("max-age=30; includeSubDomains; dummy; preload") shouldEqual
+          Right(headers.`Strict-Transport-Security`(30, true))
+      }
       "failing parse run" in {
         val Left(List(ErrorInfo(summary, detail))) = `Strict-Transport-Security`.parseFromValueString("max-age=30; includeSubDomains; preload;")
         summary shouldEqual "Illegal HTTP header 'Strict-Transport-Security': Invalid input 'EOI', expected OWS or token0 (line 1, column 40)"