diff --git a/src/data_structure/temporal_structure.jl b/src/data_structure/temporal_structure.jl
index 1673e3ff85..daa5d26612 100644
--- a/src/data_structure/temporal_structure.jl
+++ b/src/data_structure/temporal_structure.jl
@@ -378,8 +378,8 @@ end
 
 function _time_slice_set_collect_updates(t_set::TimeSliceSet)
     updates = collect(_collect_updates_many(t_set.time_slices))
-    append!(_collect_updates_many(values(t_set.gaps)))
-    append!(_collect_updates_many(values(t_set.bridges)))
+    append!(updates, _collect_updates_many(values(t_set.gaps)))
+    append!(updates, _collect_updates_many(values(t_set.bridges)))
     updates
 end