diff --git a/frame_serialize/CborUtil.h b/frame_serialize/CborUtil.h
index a4313b1e..cb016f54 100644
--- a/frame_serialize/CborUtil.h
+++ b/frame_serialize/CborUtil.h
@@ -6,6 +6,7 @@
 
 #include "tinycbor/src/cbor.h"
 
+constexpr const CborTag SelfDescribedCBOR = 55799;
 constexpr const CborTag TagMultiDimArray = 40;
 constexpr const CborTag TagDECTRISCompression = 56500;
 
diff --git a/frame_serialize/JFJochFrameDeserializer.cpp b/frame_serialize/JFJochFrameDeserializer.cpp
index 341f4ef0..13bb11ab 100644
--- a/frame_serialize/JFJochFrameDeserializer.cpp
+++ b/frame_serialize/JFJochFrameDeserializer.cpp
@@ -587,6 +587,11 @@ std::unique_lock<std::mutex> ul(m);
     CborParser parser;
     CborValue value;
     cborErr(cbor_parser_init(buffer.data(), buffer.size(), 0, &parser, &value));
+
+    if (GetCBORTag(value) != SelfDescribedCBOR)
+        throw JFJochException(JFJochExceptionCategory::CBORError, "CBOR must start with dedicated tag");
+
+
     if (cbor_value_is_map(&value)) {
         CborValue map_value;
         cborErr(cbor_value_enter_container(&value, &map_value));
diff --git a/frame_serialize/JFJochFrameSerializer.cpp b/frame_serialize/JFJochFrameSerializer.cpp
index 0754b38d..bb897b90 100644
--- a/frame_serialize/JFJochFrameSerializer.cpp
+++ b/frame_serialize/JFJochFrameSerializer.cpp
@@ -293,8 +293,9 @@ const std::vector<uint8_t> &JFJochFrameSerializer::GetBuffer() const {
 void JFJochFrameSerializer::SerializeSequenceStart(const StartMessage& message) {
     buffer.resize(max_buffer_size);
     CborEncoder encoder, mapEncoder;
-    cbor_encoder_init(&encoder, buffer.data(), buffer.size(), 0);
 
+    cbor_encoder_init(&encoder, buffer.data(), buffer.size(), 0);
+    cborErr(cbor_encode_tag(&encoder, SelfDescribedCBOR ));
     size_t elements = 27;
 
     cborErr(cbor_encoder_create_map(&encoder, &mapEncoder, elements));
@@ -344,6 +345,7 @@ void JFJochFrameSerializer::SerializeSequenceEnd(const EndMessage& message) {
 
     CborEncoder encoder, mapEncoder;
     cbor_encoder_init(&encoder, buffer.data(), buffer.size(), 0);
+    cborErr(cbor_encode_tag(&encoder, SelfDescribedCBOR ));
     cborErr(cbor_encoder_create_map(&encoder, &mapEncoder, 6));
 
     CBOR_ENC(mapEncoder, "type", "end");
@@ -364,6 +366,8 @@ void JFJochFrameSerializer::SerializeImage(const DataMessage& message) {
 
     CborEncoder encoder, mapEncoder, userDataMapEncoder;
     cbor_encoder_init(&encoder, buffer.data(), buffer.size(), 0);
+
+    cborErr(cbor_encode_tag(&encoder, SelfDescribedCBOR ));
     cborErr(cbor_encoder_create_map(&encoder, &mapEncoder, 4));
 
     CBOR_ENC(mapEncoder, "type", "image");
diff --git a/tests/CBORTest.cpp b/tests/CBORTest.cpp
index 3b6f18f3..c38b2def 100644
--- a/tests/CBORTest.cpp
+++ b/tests/CBORTest.cpp
@@ -2,7 +2,6 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 #include <catch2/catch.hpp>
-#include <nlohmann/json.hpp>
 
 #include "../frame_serialize/JFJochFrameSerializer.h"
 #include "../frame_serialize/JFJochFrameDeserializer.h"
@@ -384,23 +383,61 @@ TEST_CASE("CBORSerialize_Image_Spots", "[CBOR]") {
     REQUIRE(image_array.spots[1].intensity == 123);
 }
 
-TEST_CASE("CBORSerialize_End_NLohmann", "[CBOR]") {
+TEST_CASE("CBORSerialize_Start_stream2", "[CBOR]") {
     JFJochFrameSerializer serializer(8*1024*1024);
-    EndMessage message {
-            .number_of_images = 57789,
-            .max_receiver_delay = 3456,
-            .efficiency = 0.99,
-            .write_master_file = true,
-            .end_date = "ccc"
+
+    StartMessage message {
+            .data_file_count = 3,
+            .detector_distance = 0.0005,
+            .beam_center_x = 456.6,
+            .beam_center_y = 124.3,
+            .number_of_images = 34567,
+            .image_size_x = 456,
+            .image_size_y = 457,
+            .pixel_bit_depth = 32,
+            .pixel_signed = true,
+            .incident_energy = 12400,
+            .incident_wavelength = 0.988,
+            .frame_time = 0.0001,
+            .count_time = 0.000098,
+            .saturation_value = 65535,
+            .min_value = -32767,
+            .pixel_size_x = 0.000075,
+            .pixel_size_y = 0.000075,
+            .sensor_thickness = 0.0005,
+            .sensor_material = "Si",
+            .compression_algorithm = CompressionAlgorithm::BSHUF_LZ4,
+            .compression_block_size = 8192,
+            .unit_cell = {45,37,45,90,108,120},
+            .space_group_number = 154,
+            .max_spot_count = 250,
+            .storage_cell_number = 16,
+            .pixel_mask_enabled = true,
+            .arm_date = "abc",
+            .sample_name = "lyso",
+            .file_prefix = "lyso1/dir/file",
+            .channels = {"default", "sc2"},
+            .detector_description = "EIGER 16M",
+            .detector_serial_number = "123",
+            .series_unique_id = "bla",
+            .series_id = 4567,
+            .goniometer = {{"omega", {
+                    .increment = 0.1f,
+                    .start = 10.0f
+            }}},
+            .detector_translation = {0.5f, 0.0f, 0.5f},
+            .source_name = "Swiss Light Source",
+            .source_name_short = "SLS",
+            .instrument_name = "X06SA",
+            .instrument_name_short = "PXIII",
+            .rad_int_bin_number = 35,
+            .summation = 567
     };
+    message.pixel_mask["sc0"] = std::vector<uint32_t>(456*457, 15);
 
-    REQUIRE_NOTHROW(serializer.SerializeSequenceEnd(message));
+    REQUIRE_NOTHROW(serializer.SerializeSequenceStart(message));
+
+    auto image = serializer.GetBuffer();
 
-    auto serialized = serializer.GetBuffer();
 
-    nlohmann::json j ;
-    REQUIRE_NOTHROW(j = nlohmann::json::from_cbor(serialized));
-    REQUIRE(j["type"] == "end");
-    REQUIRE(j["write_master_file"] == true);
-    REQUIRE(j["end_date"] == "ccc");
 }
\ No newline at end of file