diff --git a/duration_utils.py b/duration_utils.py
index ee515c6..911a278 100644
--- a/duration_utils.py
+++ b/duration_utils.py
@@ -4,9 +4,10 @@
 
 import re
 
-# Seconds per unit. Supported: weeks, hours, minutes, seconds.
+# Seconds per unit. Supported: weeks, days, hours, minutes, seconds.
 _UNITS = {
     "w": 604800,
+    "d": 86400,
     "h": 3600,
     "m": 60,
     "s": 1,
diff --git a/tests/test_duration_utils.py b/tests/test_duration_utils.py
index b259480..33993d9 100644
--- a/tests/test_duration_utils.py
+++ b/tests/test_duration_utils.py
@@ -16,8 +16,12 @@ def test_seconds(self):
     def test_weeks(self):
         self.assertEqual(parse_duration("1w"), 604800)
 
+    def test_days(self):
+        self.assertEqual(parse_duration("1d"), 86400)
+
     def test_combined(self):
         self.assertEqual(parse_duration("1h30m"), 5400)
+        self.assertEqual(parse_duration("2d4h"), 187200)
 
     def test_invalid_raises(self):
         with self.assertRaises(ValueError):