The present disclosure concerns radio communication. In one of its aspects, this disclosure presents a method of assisting a receiving side PDCP entity of a network to facilitate its handling of a HFN de-synchronization incident. The method is performed by an apparatus such as a UE and comprises: while a RRC connection is in progress; detecting (120), e.g. by means of a transmitting side PDCP entity of the UE, a condition indicative of the transmitting side PDCP entity experiencing a HFN de-synchronization or a risk of HFN de-synchronization; and in response thereto maintaining (130) the RRC connection and concurrently sending a control message to the receiving side PDCP entity, the control message comprising information that the RRC connection is lasting and, thus, unbroken as well as information that the transmitting side PDCP entity is experiencing the HFN de-synchronization or the risk of HFN de-synchronization. Hereby it is made possible to allow for a limited, or reduced, signaling when handling HFN de-synchronization incidents.