diff --git a/src/oatpp/web/protocol/http/outgoing/BufferBody.cpp b/src/oatpp/web/protocol/http/outgoing/BufferBody.cpp
index c230bd88..274fb8b5 100644
--- a/src/oatpp/web/protocol/http/outgoing/BufferBody.cpp
+++ b/src/oatpp/web/protocol/http/outgoing/BufferBody.cpp
@@ -26,23 +26,24 @@
 
 namespace oatpp { namespace web { namespace protocol { namespace http { namespace outgoing {
 
-BufferBody::BufferBody(const oatpp::String& buffer, const data::share::StringKeyLabel& contentType)
+BufferBody::BufferBody(const oatpp::String &buffer, const data::share::StringKeyLabel &contentType)
   : m_buffer(buffer)
   , m_contentType(contentType)
   , m_inlineData(m_buffer->getData(), m_buffer->getSize())
 {}
 
-std::shared_ptr<BufferBody> BufferBody::createShared(const oatpp::String& buffer, const data::share::StringKeyLabel& contentType) {
+std::shared_ptr<BufferBody> BufferBody::createShared(const oatpp::String &buffer,
+                                                     const data::share::StringKeyLabel &contentType) {
   return Shared_Http_Outgoing_BufferBody_Pool::allocateShared(buffer, contentType);
 }
 
-v_io_size BufferBody::read(void *buffer, v_buff_size count, async::Action& action) {
+v_io_size BufferBody::read(void *buffer, v_buff_size count, async::Action &action) {
 
   (void) action;
 
   v_buff_size desiredToRead = m_inlineData.bytesLeft;
 
-  if(desiredToRead > 0) {
+  if (desiredToRead > 0) {
 
     if (desiredToRead > count) {
       desiredToRead = count;
@@ -59,9 +60,9 @@ v_io_size BufferBody::read(void *buffer, v_buff_size count, async::Action& actio
 
 }
 
-void BufferBody::declareHeaders(Headers& headers) {
-  if(m_contentType) {
-    headers.put(Header::CONTENT_TYPE, m_contentType);
+void BufferBody::declareHeaders(Headers &headers) {
+  if (m_contentType) {
+    headers.putIfNotExists(Header::CONTENT_TYPE, m_contentType);
   }
 }