diff --git a/src/sorunlib/seq.py b/src/sorunlib/seq.py
index 6fe880c..7d3b4d0 100644
--- a/src/sorunlib/seq.py
+++ b/src/sorunlib/seq.py
@@ -32,6 +32,10 @@ def scan(description, stop_time, width, az_drift=0, tag=None, subtype=None,
     now = dt.datetime.now(dt.timezone.utc)
     scan_stop = _timestamp_to_utc_datetime(stop_time)
 
+    # Check stop time has not already passed
+    if now > scan_stop:
+        return
+
     # Check there is enough time to perform scan
     if min_duration is not None:
         start_by_time = scan_stop - dt.timedelta(seconds=min_duration)
diff --git a/tests/test_seq.py b/tests/test_seq.py
index 74dbaab..0a09015 100644
--- a/tests/test_seq.py
+++ b/tests/test_seq.py
@@ -24,6 +24,14 @@ def test_scan(patch_clients):
     seq.scan(description='test', stop_time=target.isoformat(), width=20.)
 
 
+@patch('sorunlib._internal.time.sleep', MagicMock())
+def test_scan_passed_stop_time(patch_clients):
+    # This affects test runtime duration keep it short
+    target = dt.datetime.now(dt.timezone.utc) - dt.timedelta(seconds=10)
+    seq.scan(description='test', stop_time=target.isoformat(), width=20.)
+    seq.run.CLIENTS['acu'].generate_scan.start.assert_not_called()
+
+
 @patch('sorunlib._internal.time.sleep', MagicMock())
 def test_scan_passed_min_duration(patch_clients):
     # This affects test runtime duration keep it short