diff --git a/db/system_keyspace.cc b/db/system_keyspace.cc
index 42f99ac77f..ad61fde923 100644
--- a/db/system_keyspace.cc
+++ b/db/system_keyspace.cc
@@ -3347,11 +3347,11 @@ mutation system_keyspace::make_group0_history_state_id_mutation(
         using namespace std::chrono;
         assert(*gc_older_than >= gc_clock::duration{0});
 
-        auto ts_millis = duration_cast<milliseconds>(microseconds{ts});
-        auto gc_older_than_millis = duration_cast<milliseconds>(*gc_older_than);
-        assert(gc_older_than_millis < ts_millis);
+        auto ts_micros = microseconds{ts};
+        auto gc_older_than_micros = duration_cast<microseconds>(*gc_older_than);
+        assert(gc_older_than_micros < ts_micros);
 
-        auto tomb_upper_bound = utils::UUID_gen::min_time_UUID(ts_millis - gc_older_than_millis);
+        auto tomb_upper_bound = utils::UUID_gen::min_time_UUID(ts_micros - gc_older_than_micros);
         // We want to delete all entries with IDs smaller than `tomb_upper_bound`
         // but the deleted range is of the form (x, +inf) since the schema is reversed.
         auto range = query::clustering_range::make_starting_with({
diff --git a/utils/UUID_gen.hh b/utils/UUID_gen.hh
index d2a69d1e6f..9f032e7620 100644
--- a/utils/UUID_gen.hh
+++ b/utils/UUID_gen.hh
@@ -289,7 +289,7 @@ public:
      * <b>Warning:</b> this method should only be used for querying as this
      * doesn't at all guarantee the uniqueness of the resulting UUID.
      */
-    static UUID min_time_UUID(milliseconds timestamp = milliseconds{0})
+    static UUID min_time_UUID(decimicroseconds timestamp = decimicroseconds{0})
     {
         auto uuid = UUID(create_time(from_unix_timestamp(timestamp)), MIN_CLOCK_SEQ_AND_NODE);
         assert(uuid.is_timestamp());