diff --git a/src/content/content-manager.cpp b/src/content/content-manager.cpp
index 0eb453329..ce6fe3545 100644
--- a/src/content/content-manager.cpp
+++ b/src/content/content-manager.cpp
@@ -23,8 +23,6 @@
 #include "content-type.h"
 #include "content/content.h"
 
-#define MULTIPART_BOUNDARY "---------------------------14737809831466499882746641449"
-
 // =============================================================================
 
 using namespace std;
diff --git a/src/content/content-type.cpp b/src/content/content-type.cpp
index 66b22e7f9..93e27859c 100644
--- a/src/content/content-type.cpp
+++ b/src/content/content-type.cpp
@@ -45,7 +45,7 @@ const ContentType ContentType::ExternalBody("message/external-body");
 const ContentType ContentType::FileTransfer("application/vnd.gsma.rcs-ft-http+xml");
 const ContentType ContentType::Imdn("message/imdn+xml");
 const ContentType ContentType::ImIsComposing("application/im-iscomposing+xml");
-const ContentType ContentType::Multipart("multipart/mixed");
+const ContentType ContentType::Multipart("multipart/mixed;boundary=" MULTIPART_BOUNDARY);
 const ContentType ContentType::PlainText("text/plain");
 const ContentType ContentType::ResourceLists("application/resource-lists+xml");
 const ContentType ContentType::Sdp("application/sdp");
diff --git a/src/content/content-type.h b/src/content/content-type.h
index d37168f08..473b0ab80 100644
--- a/src/content/content-type.h
+++ b/src/content/content-type.h
@@ -22,6 +22,9 @@
 
 #include "object/clonable-object.h"
 
+
+#define MULTIPART_BOUNDARY "---------------------------14737809831466499882746641449"
+
 // =============================================================================
 
 LINPHONE_BEGIN_NAMESPACE