diff --git a/Tools/msg/px_generate_uorb_compressed_fields.py b/Tools/msg/px_generate_uorb_compressed_fields.py
index bcd2287e4f..f654eef440 100755
--- a/Tools/msg/px_generate_uorb_compressed_fields.py
+++ b/Tools/msg/px_generate_uorb_compressed_fields.py
@@ -146,6 +146,7 @@ def write_fields_to_hpp_file(file_name: str, definitions: dict, window_length: i
                              format_list: [str]):
     max_tokenized_field_length, max_tokenized_field_length_msg = max(
         ((len(definitions[k]['fields']), k) for k in definitions), key=itemgetter(0))
+    max_untokenized_field_length = max(definitions[k]['fields_total_length'] for k in definitions)
     max_num_orb_ids = max(len(definitions[k]['orb_ids']) for k in definitions)
     max_num_orb_id_dependencies = max(len(definitions[k]['dependencies']) for k in definitions)
 
@@ -167,6 +168,7 @@ const uint8_t* orb_compressed_message_formats();
 unsigned orb_compressed_message_formats_size();
 
 static constexpr unsigned orb_tokenized_fields_max_length = {MAX_TOKENIZED_FIELD_LENGTH}; // {MAX_TOKENIZED_FIELD_LENGTH_MSG}
+static constexpr unsigned orb_untokenized_fields_max_length = {MAX_UNTOKENIZED_FIELD_LENGTH};
 static constexpr unsigned orb_compressed_max_num_orb_ids = {MAX_NUM_ORB_IDS};
 static constexpr unsigned orb_compressed_max_num_orb_id_dependencies = {MAX_NUM_ORB_ID_DEPENDENCIES};
 
@@ -179,6 +181,7 @@ static constexpr unsigned orb_compressed_heatshrink_lookahead_length = {LOOKAHEA
 '''
                           .replace('{MAX_TOKENIZED_FIELD_LENGTH}', str(max_tokenized_field_length))
                           .replace('{MAX_TOKENIZED_FIELD_LENGTH_MSG}', max_tokenized_field_length_msg)
+                          .replace('{MAX_UNTOKENIZED_FIELD_LENGTH}', str(max_untokenized_field_length))
                           .replace('{MAX_NUM_ORB_IDS}', str(max_num_orb_ids))
                           .replace('{MAX_NUM_ORB_ID_DEPENDENCIES}', str(max_num_orb_id_dependencies))
                           .replace('{WINDOW_LENGTH}', str(window_length))
diff --git a/Tools/msg/templates/uorb/msg.json.em b/Tools/msg/templates/uorb/msg.json.em
index 4f6a9111ad..31be5d61aa 100644
--- a/Tools/msg/templates/uorb/msg.json.em
+++ b/Tools/msg/templates/uorb/msg.json.em
@@ -42,6 +42,7 @@ for field in spec.parsed_fields():
 {
 @# join all msg files in one line e.g: "float[3] position;float[3] velocity;bool armed;"
 		"fields": @( json.dumps(bytearray(";".join(topic_fields)+";", 'utf-8').decode('unicode_escape')) ),
+		"fields_total_length": @(sum([len(convert_type(field.type))+1+len(field.name)+1 for field in sorted_fields])),
 		"orb_ids": @( json.dumps([ all_topics.index(topic) for topic in topics]) ),
 		"main_orb_id": @( all_topics.index(name_snake_case) if name_snake_case in all_topics else -1 ),
 		"dependencies": @( json.dumps(list(set(dependencies))) ),
diff --git a/platforms/common/uORB/uORBMessageFieldsTest.cpp b/platforms/common/uORB/uORBMessageFieldsTest.cpp
index 03d25b9a26..f677d9737e 100644
--- a/platforms/common/uORB/uORBMessageFieldsTest.cpp
+++ b/platforms/common/uORB/uORBMessageFieldsTest.cpp
@@ -53,7 +53,10 @@ public:
 
 TEST_F(uORBMessageFieldsTest, decompressed_formats_match)
 {
-	char buffer[1500];
+	char buffer[1600];
+	static_assert(uORB::orb_untokenized_fields_max_length < sizeof(buffer) - HEATSHRINK_DECODER_INPUT_BUFFER_SIZE(_),
+		      "msg definition too long / buffer too short");
+
 	uORB::MessageFormatReader format_reader(buffer, sizeof(buffer));
 
 	px4::Bitset<ORB_TOPICS_COUNT> formats_found;
diff --git a/src/modules/logger/logger.cpp b/src/modules/logger/logger.cpp
index 89b3cfe50d..ecb05295d6 100644
--- a/src/modules/logger/logger.cpp
+++ b/src/modules/logger/logger.cpp
@@ -69,6 +69,10 @@
 
 //#define DBGPRINT //write status output every few seconds
 
+static_assert(uORB::orb_untokenized_fields_max_length < sizeof(ulog_message_format_s::format) -
+	      HEATSHRINK_DECODER_INPUT_BUFFER_SIZE(_),
+	      "msg definition too long / buffer too short");
+
 #if defined(DBGPRINT)
 // needed for mallinfo
 #if defined(__PX4_POSIX) && !defined(__PX4_DARWIN)