diff --git a/v2/server.go b/v2/server.go
index b5f5f01..8d26539 100644
--- a/v2/server.go
+++ b/v2/server.go
@@ -146,7 +146,7 @@ func (s *Server) HasMethod(method string) bool {
 // ServeHTTP
 func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	if r.Method != "POST" {
-		WriteError(w, 405, "rpc: POST method required, received "+r.Method)
+		WriteError(w, http.StatusMethodNotAllowed, "rpc: POST method required, received "+r.Method)
 		return
 	}
 	contentType := r.Header.Get("Content-Type")
@@ -162,7 +162,7 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			codec = c
 		}
 	} else if codec = s.codecs[strings.ToLower(contentType)]; codec == nil {
-		WriteError(w, 415, "rpc: unrecognized Content-Type: "+contentType)
+		WriteError(w, http.StatusUnsupportedMediaType, "rpc: unrecognized Content-Type: "+contentType)
 		return
 	}
 	// Create a new codec request.
@@ -170,18 +170,18 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// Get service method to be called.
 	method, errMethod := codecReq.Method()
 	if errMethod != nil {
-		codecReq.WriteError(w, 400, errMethod)
+		codecReq.WriteError(w, http.StatusBadRequest, errMethod)
 		return
 	}
 	serviceSpec, methodSpec, errGet := s.services.get(method)
 	if errGet != nil {
-		codecReq.WriteError(w, 400, errGet)
+		codecReq.WriteError(w, http.StatusBadRequest, errGet)
 		return
 	}
 	// Decode the args.
 	args := reflect.New(methodSpec.argsType)
 	if errRead := codecReq.ReadRequest(args.Interface()); errRead != nil {
-		codecReq.WriteError(w, 400, errRead)
+		codecReq.WriteError(w, http.StatusBadRequest, errRead)
 		return
 	}
 
@@ -227,18 +227,22 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	// Extract the result to error if needed.
 	var errResult error
-	if !errValue[0].IsNil() {
-		errResult = errValue[0].Interface().(error)
+	statusCode := http.StatusOK
+	errInter := errValue[0].Interface()
+	if errInter != nil {
+		statusCode = http.StatusBadRequest
+		errResult = errInter.(error)
 	}
 
 	// Prevents Internet Explorer from MIME-sniffing a response away
 	// from the declared content-type
 	w.Header().Set("x-content-type-options", "nosniff")
+
 	// Encode the response.
 	if errResult == nil {
 		codecReq.WriteResponse(w, reply.Interface())
 	} else {
-		codecReq.WriteError(w, 400, errResult)
+		codecReq.WriteError(w, statusCode, errResult)
 	}
 
 	// Call the registered After Function
@@ -247,7 +251,7 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			Request:    r,
 			Method:     method,
 			Error:      errResult,
-			StatusCode: 200,
+			StatusCode: statusCode,
 		})
 	}
 }