diff --git a/modules/core/src/smithy4s/http/HttpUnaryServerCodecs.scala b/modules/core/src/smithy4s/http/HttpUnaryServerCodecs.scala
index 6876060ce..4ab0448ed 100644
--- a/modules/core/src/smithy4s/http/HttpUnaryServerCodecs.scala
+++ b/modules/core/src/smithy4s/http/HttpUnaryServerCodecs.scala
@@ -194,8 +194,14 @@ object HttpUnaryServerCodecs {
 
           def encodeOutput(o: O) = F.map(base)(outputW.write(_, o))
           def encodeError(e: E) = F.map(base)(errorW.write(_, e))
-          def httpContractErrorEncoder(e: HttpContractError) =
-            F.map(base)(httpContractErrorWriters.write(_, e).withStatusCode(400))
+
+          def httpContractErrorEncoder(e: HttpContractError) = {
+            val statusCode = e match {
+              case _: UpstreamServiceError => 500
+              case _ => 400
+            }
+            F.map(base)(httpContractErrorWriters.write(_, e).withStatusCode(statusCode))
+          }
           def throwableEncoders(throwable: Throwable): F[HttpResponse[Blob]] =
             throwable match {
               case e: HttpContractError => httpContractErrorEncoder(e)
diff --git a/modules/tests/src/smithy4s/tests/PizzaAdminServiceImpl.scala b/modules/tests/src/smithy4s/tests/PizzaAdminServiceImpl.scala
index 702fe0f53..406a85144 100644
--- a/modules/tests/src/smithy4s/tests/PizzaAdminServiceImpl.scala
+++ b/modules/tests/src/smithy4s/tests/PizzaAdminServiceImpl.scala
@@ -20,6 +20,7 @@ import cats.effect._
 import cats.implicits._
 import smithy4s.Timestamp
 import smithy4s.example._
+import smithy4s.http.UpstreamServiceError
 
 import java.util.UUID
 
@@ -51,6 +52,7 @@ class PizzaAdminServiceImpl(ref: Ref[IO, State]) extends PizzaAdminService[IO] {
   ): IO[AddMenuItemResult] =
     for {
       _ <- IO.raiseError(Boom).whenA(restaurant == "boom")
+      _ <- IO.raiseError(UpstreamServiceError("Upstream service failure")).whenA(restaurant == "upstreamServiceError")
       _ <- IO
         .raiseError(
           PriceError(
diff --git a/modules/tests/src/smithy4s/tests/PizzaSpec.scala b/modules/tests/src/smithy4s/tests/PizzaSpec.scala
index b17982521..fb691ed63 100644
--- a/modules/tests/src/smithy4s/tests/PizzaSpec.scala
+++ b/modules/tests/src/smithy4s/tests/PizzaSpec.scala
@@ -30,6 +30,7 @@ import smithy4s.http.HttpPayloadError
 import smithy4s.example.PizzaAdminService
 import smithy4s.http.CaseInsensitive
 import smithy4s.http.HttpContractError
+import smithy4s.http.UpstreamServiceError
 import weaver._
 import cats.Show
 import org.http4s.EntityDecoder
@@ -463,6 +464,33 @@ abstract class PizzaSpec
       }
   }
 
+  routerTest("Upstream service error returns 500") { (client, uri, log) =>
+    val badMenuItem = Json.obj(
+      "food" -> pizzaItem,
+      "price" -> Json.fromFloatOrNull(9.0f)
+    )
+
+    for {
+      res <- client.send[Json](
+        POST(badMenuItem, uri / "restaurant" / "upstreamServiceError" / "menu" / "item"),
+        log
+      )
+    } yield {
+      val (code, headers, body) = res
+      val expectedBody =
+        Json.obj(
+          "upstreamServiceError" -> Json.obj(
+            "message" -> Json.fromString("Upstream service failure")
+          )
+        )
+     val discriminator = headers.get("X-Error-Type").flatMap(_.headOption)
+
+      expect(code == 500) &&
+        expect(body == expectedBody) &&
+        expect(discriminator == None)
+    }
+  }
+
   type Res = (Client[IO], Uri)
   def sharedResource: Resource[IO, (Client[IO], Uri)] = for {
     stateRef <- Resource.eval(
@@ -476,6 +504,8 @@ abstract class PizzaSpec
           smithy4s.example.GenericClientError("Oops")
         case PizzaAdminServiceImpl.Boom =>
           smithy4s.example.GenericServerError("Crash")
+        case UpstreamServiceError(message) =>
+          UpstreamServiceError(message)
         case t: Throwable if !t.isInstanceOf[HttpContractError] =>
           // This pattern allows checking that errors specified in specs
           // do not get intercepted by mapErrors/flatMapErrors methods.