diff --git a/src/data_structure/temporal_structure.jl b/src/data_structure/temporal_structure.jl
index 4fee1e147b..2103f8b988 100644
--- a/src/data_structure/temporal_structure.jl
+++ b/src/data_structure/temporal_structure.jl
@@ -355,11 +355,19 @@ function _generate_time_slice_relationships!(m::Model)
     succeeding_time_slices = Dict(
         t => to_time_slice(m, t=TimeSlice(end_(t), end_(t) + Minute(1))) for t in all_time_slices
     )
-    succeeding_time_slices_hist = Dict(
-        last(history_time_slices) => [first(time_slice(m; temporal_block=blk))]
-        for (blk, history_time_slices) in m.ext[:spineopt].temporal_structure[:history_time_slice].block_time_slices
-    )
-    merge!(append!, succeeding_time_slices, succeeding_time_slices_hist)
+    if m.ext[:spineopt].temporal_structure[:window_count] > 1
+        # Ensure continuity on the window boundary.
+        # This is needed in case a block ends before the window, or starts after the window.
+        # When that's the case, there is a gap on the window boundary
+        # that would result in 'transition' constraints not being properly enforced
+        # (and thus, for instance, free units started at the beginning of each window)
+        # Here we bridge that gap in t_before_t
+        succeeding_time_slices_hist = Dict(
+            last(history_time_slices) => [first(time_slice(m; temporal_block=blk))]
+            for (blk, history_time_slices) in m.ext[:spineopt].temporal_structure[:history_time_slice].block_time_slices
+        )
+        merge!(append!, succeeding_time_slices, succeeding_time_slices_hist)
+    end
     overlapping_time_slices = Dict(t => to_time_slice(m, t=t) for t in all_time_slices)
     overlapping_time_slices_excl = Dict(
         t => setdiff(time_slices, t) for (t, time_slices) in overlapping_time_slices