diff --git a/uavcan/time/62804.Synchronization.1.0.uavcan b/uavcan/time/62804.Synchronization.1.0.uavcan
index d418801d..89c7ef6e 100644
--- a/uavcan/time/62804.Synchronization.1.0.uavcan
+++ b/uavcan/time/62804.Synchronization.1.0.uavcan
@@ -16,7 +16,8 @@ uint8 PUBLISHER_TIMEOUT_PERIOD_MULTIPLIER = 3
 
 # The time when the PREVIOUS message was transmitted from the current publisher.
 # If this message is published for the first time, this field must be zero.
-SystemTime.1 previous_transmission_timestamp
+TimeReference.0.1 reference
+truncated uint53 duration
 
 @assert offset % 8 == {0}
 @assert offset.max <= 56    # Must fit into one CAN 2.0 frame (least capable transport, smallest MTU)
diff --git a/uavcan/time/Duration.1.0.uavcan b/uavcan/time/Duration.1.0.uavcan
deleted file mode 100644
index 4d1f1d86..00000000
--- a/uavcan/time/Duration.1.0.uavcan
+++ /dev/null
@@ -1,13 +0,0 @@
-#
-# Data type used for representing a duration since a contextually defomed event in time with microsecond resolution.
-# This data type can both be used to build higher level abstractions such as `SystemTime` and `Instant` or be used directly.
-#
-
-# This value is to never overflow. The value is 53-bit wide because:
-#
-#   - 2^53 microseconds is about 285 years, which is enough. A 64-bit microsecond counter would be
-#     unnecessarily wide and its overflow interval of 585 thousand years induces a mild existential crisis.
-#
-#   - CAN 2.0-based transports carry up to 7 bytes per frame. Time sync messages must use single-frame
-#     transfers, which means that the `SystemTime` type can't be wider than 56 bits.
-truncated uint53 microseconds
diff --git a/uavcan/time/SystemTime.1.0.uavcan b/uavcan/time/SystemTime.1.0.uavcan
deleted file mode 100644
index 8141fe46..00000000
--- a/uavcan/time/SystemTime.1.0.uavcan
+++ /dev/null
@@ -1,24 +0,0 @@
-#
-# The System Time defines a point in time in a concrete time reference.
-#
-# The moment of origin is defined per-application. Commonly chosen time bases are:
-#   - GPS time (other satellite positioning systems use different incompatible time bases)
-#   - TAI
-#   - In simple centralized applications: the local monotonic clock of the central controller
-
-# Local time since boot. A convinient fallback if no global time sync is available.
-uint3 REFERENCE_BOOT = 0 
-# Time defined as in Unix time since Jan 1. 1970.
-uint3 REFERENCE_UNIX = 1 
-# Time defined as in GPS Time since Jan 6. 1980.
-uint3 REFERENCE_GPST = 2
-# Time defined as in international atomic time since Jan 1. 1977. 
-uint3 REFERENCE_TAI = 3 
-
-# 4, 5 and 6 is reserved for backward compatible future extensions. Do not use!
-
-uint3 REFERENCE_APPLICATION_TIME_1 = 7 # A custom (application dependent) time reference.
-
-uint3 reference
-
-Duration.1 time
diff --git a/uavcan/time/TimeReference.0.1.uavcan b/uavcan/time/TimeReference.0.1.uavcan
new file mode 100644
index 00000000..e69de29b