diff --git a/goodwe_controller/test_opt36.py b/goodwe_controller/test_opt36.py
index 4001e60..869161c 100644
--- a/goodwe_controller/test_opt36.py
+++ b/goodwe_controller/test_opt36.py
@@ -44,7 +44,7 @@ sys.path.insert(0, HERE)
 sys.path.insert(0, os.path.join(HERE, "tools"))
 logging.disable(logging.WARNING)
 
-from named_absence import nth                                   # noqa: E402
+from named_absence import nth, present                          # noqa: E402
 import ux54_scenarios as S                                      # noqa: E402
 import opt11p3_replay as rp                                     # noqa: E402
 import app.main as m                                            # noqa: E402
@@ -793,12 +793,14 @@ check("mid night: A's commands follow the levels: it charges to its level "
       md["soc"][0] < 85.0 and abs(md["soc"][0] - m2["target_a"]) < 0.5)
 check("mid night: B fills as before (to the ceiling)", md["soc"][1] > 94.0)
 mf = R["mid_flat"]
-lv_f = {mk["target_a"] for mk in mf["marks"].values()}
-print(f"    mid_flat: A level(s) {sorted(lv_f)}; A ends {mf['soc'][0]:.2f} %")
+lv_f = [mk["target_a"] for mk in mf["marks"].values()]
+lv0 = nth(lv_f, 0)
+print(f"    mid_flat: A level(s) {sorted(set(map(str, lv_f)))}; A ends "
+      f"{mf['soc'][0]:.2f} %")
 check("one figure all night: A's level never moves (round 2: 55 -> 69 -> "
       "41 -> 37 %), A charges to it and stops (round 2: 56 %)",
-      len(lv_f) == 1 and None not in lv_f
-      and abs(mf["soc"][0] - next(iter(lv_f))) < 0.5)
+      present(lv0) and lv0 is not None and len(set(lv_f)) == 1
+      and abs(mf["soc"][0] - lv0) < 0.5)
 fd = R["f1_dark_b"]
 dk = fd["marks"]
 held = [dk[h]["target_a"] for h in dk if "05:15" <= h < "07:00"]