diff --git a/routes/calendar_routes.py b/routes/calendar_routes.py
index 4509c3f..bd2b443 100644
--- a/routes/calendar_routes.py
+++ b/routes/calendar_routes.py
@@ -338,8 +338,8 @@ def _parse_dt(s: str) -> datetime:
             return None
         return h, mn
 
-    # today/tomorrow/yesterday [at] TIME
-    m = _re.match(r'^(today|tomorrow|tmrw|yesterday)(?:\s+at)?\s*(.*)$', lower)
+    # today/tonight/tomorrow/yesterday [at] TIME
+    m = _re.match(r'^(today|tonight|tomorrow|tmrw|yesterday)(?:\s+at)?\s*(.*)$', lower)
     if m:
         word, rest = m.group(1), m.group(2).strip()
         base = today
diff --git a/tests/test_calendar_parse_dt_tonight.py b/tests/test_calendar_parse_dt_tonight.py
new file mode 100644
index 0000000..93cc991
--- /dev/null
+++ b/tests/test_calendar_parse_dt_tonight.py
@@ -0,0 +1,26 @@
+"""Regression: _parse_dt must understand "tonight" like parse_due_for_user does.
+
+parse_due_for_user's natural-language regex accepts
+`(today|tonight|tomorrow|tmrw|yesterday)`, but _parse_dt (the parser
+_parse_dt_pair falls back to for calendar event start/end) only had
+`(today|tomorrow|tmrw|yesterday)`. So an event start like "tonight at 9pm"
+missed the today-branch and fell through to dateutil, which does not know the
+word "tonight" and raises, breaking event creation for a phrasing that works
+fine for reminders. "tonight" is now handled, mapped to today like the sibling.
+"""
+from routes.calendar_routes import _parse_dt
+
+
+def test_tonight_with_time_parses_to_today_evening():
+    got = _parse_dt("tonight at 9pm")
+    ref = _parse_dt("today at 9pm")
+    assert got.hour == 21 and got.minute == 0
+    assert got.date() == ref.date()
+
+
+def test_bare_tonight_is_today():
+    assert _parse_dt("tonight").date() == _parse_dt("today").date()
+
+
+def test_tonight_matches_today_time_exactly():
+    assert _parse_dt("tonight at 7:30pm") == _parse_dt("today at 7:30pm")