--- a/netwerk/sctp/datachannel/DataChannel.h
+++ b/netwerk/sctp/datachannel/DataChannel.h
@@ -75,17 +75,17 @@ protected:
   size_t mPos;
 };
 
 // For queuing outgoing messages
 // This class copies data of an outgoing message.
 class BufferedOutgoingMsg : public OutgoingMsg
 {
 public:
-  BufferedOutgoingMsg(OutgoingMsg &message);
+  explicit BufferedOutgoingMsg(OutgoingMsg &message);
   ~BufferedOutgoingMsg();
 };
 
 // for queuing incoming data messages before the Open or
 // external negotiation is indicated to us
 class QueuedDataMessage
 {
 public: