diff --git a/coreapi/chat.c b/coreapi/chat.c
index 4a4ebc7d9..eb0839631 100644
--- a/coreapi/chat.c
+++ b/coreapi/chat.c
@@ -679,6 +679,11 @@ LinphoneReason linphone_core_message_received(LinphoneCore *lc, SalOp *op, const
 			} else if(retval > 0) {
 				// Unable to decrypt message
 				linphone_core_notify_message_received_unable_decrypt(cr->lc, cr, msg);
+				reason = linphone_error_code_to_reason(retval);
+				linphone_chat_message_send_delivery_notification(msg, reason);
+				// return LinphoneReasonNone to avoid flexisip resending us a message we can't decrypt
+				reason = LinphoneReasonNone;
+				goto end;
 			}
 		}
 	}
diff --git a/tester/message_tester.c b/tester/message_tester.c
index 702c96a5c..4931dce6c 100644
--- a/tester/message_tester.c
+++ b/tester/message_tester.c
@@ -1260,7 +1260,7 @@ static void lime_text_message_to_non_lime(bool_t sender_policy_mandatory, bool_t
 		if (chat_room_size == 1) {
 			bctbx_list_t *history = linphone_chat_room_get_history(chat_room, 0);
 			LinphoneChatMessage *sent_msg = (LinphoneChatMessage *)bctbx_list_get_data(history);
-			BC_ASSERT_EQUAL((int)linphone_chat_message_get_state(sent_msg), (int)LinphoneChatMessageStateNotDelivered, int, "%d");
+			BC_ASSERT_EQUAL((int)linphone_chat_message_get_state(sent_msg), (int)LinphoneChatMessageStateDelivered, int, "%d");
 			bctbx_list_free_with_data(history, (bctbx_list_free_func)linphone_chat_message_unref);
 		}
 	} else {