diff --git a/include/param/param.h b/include/param/param.h
index 4b31782..dfc872f 100644
--- a/include/param/param.h
+++ b/include/param/param.h
@@ -86,12 +86,6 @@ typedef enum {
 #define PM_CSP               (5 << 16) //! Known as 5 in elfparse and genparamtable
 #define PM_KEYCONF               (6 << 16) //! Known as 6 in elfparse and genparamtable
 
-/**
- * Value to indicate an invalid nsec.
- *
- * This define should be moved to CSP if CSP will have support for invalid nsec
- */
-#define CSP_TIMESTAMP_INVALID_NSEC	-1
 
 /**
  * Parameter description structure
@@ -146,7 +140,7 @@ typedef struct param_s {
 
 #ifdef PARAM_HAVE_TIMESTAMP
 #define PARAM_TIMESTAMP_DECL(_name) \
-    csp_timestamp_t _timestamp_##_name = { .tv_sec = 0, .tv_nsec = CSP_TIMESTAMP_INVALID_NSEC };
+    csp_timestamp_t _timestamp_##_name = { .tv_sec = 0, .tv_nsec = 0 };
 
 #define PARAM_TIMESTAMP_INIT(_name) \
     .timestamp = &_timestamp_##_name,
diff --git a/meson.build b/meson.build
index de243f9..320bb9d 100644
--- a/meson.build
+++ b/meson.build
@@ -24,10 +24,6 @@ if get_option('have_float') == false
 	conf.set('MPACK_FLOAT', 0)
 endif
 
-if get_option('serialize_extended_timestamp') == true
-	conf.set('EXTENDED_TIMESTAMP', 1)
-endif
-
 if get_option('have_fopen') == true
 	if get_option('list_dynamic') == true
 		conf.set('MPACK_STDIO', 1)
diff --git a/meson_options.txt b/meson_options.txt
index 5053071..a1c5765 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -6,5 +6,4 @@ option('list_dynamic', type: 'boolean', value: false, description: 'Compile supp
 option('list_pool', type: 'integer', value: 0, description: 'Compile support for pre-allocated param list (requres sys/queue.h)')
 option('have_float', type: 'boolean', value: true, description: 'Support float/double')
 option('num_publishqueues', type: 'integer', value: 0, description: 'Number of param publish queues required')
-option('serialize_extended_timestamp', type: 'boolean', value: false, description: 'Include ns part of timestamps when serializing parameters (network incompatible with libparam older than June 2025')
 option('test', type: 'boolean', value: false, description: 'Build GoogleTest based tests (requires gtest)')
diff --git a/src/param/param_queue.c b/src/param/param_queue.c
index 237db59..54c2896 100644
--- a/src/param/param_queue.c
+++ b/src/param/param_queue.c
@@ -36,7 +36,7 @@ void param_queue_init(param_queue_t *queue, void *buffer, int buffer_size, int u
 	queue->used = used;
 	queue->version = version;
 	queue->last_timestamp.tv_sec = 0;
-	queue->last_timestamp.tv_nsec = CSP_TIMESTAMP_INVALID_NSEC;
+	queue->last_timestamp.tv_nsec = 0;
 }
 
 int param_queue_add(param_queue_t *queue, param_t *param, int offset, void *value) {
diff --git a/src/param/param_serializer.c b/src/param/param_serializer.c
index 232f44b..f8434e4 100644
--- a/src/param/param_serializer.c
+++ b/src/param/param_serializer.c
@@ -70,20 +70,14 @@ void param_serialize_id(mpack_writer_t *writer, param_t *param, int offset, para
 		int node_flag = (queue->last_node != node) ? 1 : 0;
 #ifdef PARAM_HAVE_TIMESTAMP
 		int timestamp_flag = (queue->last_timestamp.tv_sec != param->timestamp->tv_sec) ? 1 : 0;
-		int extendedtimestamp_flag = 0;
-#ifdef EXTENDED_TIMESTAMP
-		extendedtimestamp_flag = (queue->last_timestamp.tv_nsec != param->timestamp->tv_nsec) ? 1 : 0;
-#endif /* EXTENDED_TIMESTAMP */
 #else
 		int timestamp_flag = 0;
-		int extendedtimestamp_flag = 0;
 #endif
 		int extendedid_flag = (param->id > 0x3ff) ? 1 : 0;
 
-		uint16_t header = array_flag << PARAM_HEADER_ARRAY_POS
+		uint16_t header = array_flag << PARAM_HEADER_ARRAY_POS 
 						| node_flag << PARAM_HEADER_NODE_POS
 						| timestamp_flag << PARAM_HEADER_TIMESTAMP_POS
-						| extendedtimestamp_flag << PARAM_HEADER_EXTENDEDTIMESTAMP_POS
 						| extendedid_flag << PARAM_HEADER_EXTENDEDID_POS
 						|(param->id & PARAM_HEADER_ID_MASK);
 		header = htobe16(header);
@@ -106,12 +100,6 @@ void param_serialize_id(mpack_writer_t *writer, param_t *param, int offset, para
 			uint32_t _timestamp = htobe32(param->timestamp->tv_sec);
 			mpack_write_bytes(writer, (char*) &_timestamp, 4);
 		}
-
-		if (extendedtimestamp_flag) {
-			queue->last_timestamp.tv_nsec = param->timestamp->tv_nsec;
-			uint32_t _timestamp_ns = htobe32(param->timestamp->tv_nsec);
-			mpack_write_bytes(writer, (char*) &_timestamp_ns, 4);
-		}
 #endif
 
 		if (extendedid_flag) {
@@ -178,14 +166,19 @@ void param_deserialize_id(mpack_reader_t *reader, int *id, int *node, csp_timest
 			_timestamp = be32toh(_timestamp);
 			if (_timestamp != 0) {
 				queue->last_timestamp.tv_sec = _timestamp;
+				if (extendedtimestamp_flag) {
+					uint32_t _timestamp_ns;
+					mpack_read_bytes(reader, (char*) &_timestamp_ns, 4);
+					_timestamp_ns = be32toh(_timestamp_ns);
+					queue->last_timestamp.tv_nsec = _timestamp_ns;
+				} else {
+					queue->last_timestamp.tv_nsec = 0;
+				}
 			}
-		}
-
-		if (extendedtimestamp_flag) {
+		} else if (extendedtimestamp_flag) {
+			/* Invalid header combination, discard header field */
 			uint32_t _timestamp_ns;
 			mpack_read_bytes(reader, (char*) &_timestamp_ns, 4);
-			_timestamp_ns = be32toh(_timestamp_ns);
-			queue->last_timestamp.tv_nsec = _timestamp_ns;
 		}
 		*timestamp = queue->last_timestamp;