diff --git a/README.md b/README.md
index 2177d0a..89d9d43 100644
--- a/README.md
+++ b/README.md
@@ -42,58 +42,53 @@ This will be the datetime parsing logic for [pydantic-core](https://github.com/p
 ```rust
 use speedate::{DateTime, Date, Time};
 
-fn main() {
-    let dt = DateTime::parse_str("2022-01-01T12:13:14Z").unwrap();
-    assert_eq!(
-        dt,
-        DateTime {
-            date: Date {
-                year: 2022,
-                month: 1,
-                day: 1,
-            },
-            time: Time {
-                hour: 12,
-                minute: 13,
-                second: 14,
-                microsecond: 0,
-                tz_offset: Some(0),
-            },
-        }
-    );
-    assert_eq!(dt.to_string(), "2022-01-01T12:13:14Z");
-}
+let dt = DateTime::parse_str("2022-01-01T12:13:14Z").unwrap();
+assert_eq!(
+    dt,
+    DateTime {
+        date: Date {
+            year: 2022,
+            month: 1,
+            day: 1,
+        },
+        time: Time {
+            hour: 12,
+            minute: 13,
+            second: 14,
+            microsecond: 0,
+            tz_offset: Some(0),
+        },
+    }
+);
+assert_eq!(dt.to_string(), "2022-01-01T12:13:14Z");
 ```
 
 To control the specifics of time parsing you can use provide a `TimeConfig`:
 
 ```rust
 use speedate::{DateTime, Date, Time, TimeConfig};
-
-fn main() {
-    let dt = DateTime::parse_bytes_with_config(
-        "1689102037.5586429".as_bytes(),
-        &TimeConfig::builder().unix_timestamp_offset(Some(0)).build(),
-    ).unwrap();
-    assert_eq!(
-        dt,
-        DateTime {
-            date: Date {
-                year: 2023,
-                month: 7,
-                day: 11,
-            },
-            time: Time {
-                hour: 19,
-                minute: 0,
-                second: 37,
-                microsecond: 558643,
-                tz_offset: Some(0),
-            },
-        }
-    );
-    assert_eq!(dt.to_string(), "2023-07-11T19:00:37.558643Z");
-}
+let dt = DateTime::parse_bytes_with_config(
+    "1689102037.5586429".as_bytes(),
+    &TimeConfig::builder().unix_timestamp_offset(Some(0)).build(),
+).unwrap();
+assert_eq!(
+    dt,
+    DateTime {
+        date: Date {
+            year: 2023,
+            month: 7,
+            day: 11,
+        },
+        time: Time {
+            hour: 19,
+            minute: 0,
+            second: 37,
+            microsecond: 558643,
+            tz_offset: Some(0),
+        },
+    }
+);
+assert_eq!(dt.to_string(), "2023-07-11T19:00:37.558643Z");
 ```
 
 ## Performance
diff --git a/src/duration.rs b/src/duration.rs
index 8fde0dc..c45d776 100644
--- a/src/duration.rs
+++ b/src/duration.rs
@@ -298,10 +298,13 @@ impl Duration {
         };
         let mut d = match bytes.get(offset).copied() {
             Some(b'P') => Self::parse_iso_duration(bytes, offset + 1),
-            _ => match bytes.get(offset + 2).copied() {
-                Some(b':') => Self::parse_time(bytes, offset, config),
-                _ => Self::parse_days_time(bytes, offset),
-            },
+            _ => {
+                if Self::is_duration_date_format(bytes) || bytes.len() < 5 {
+                    Self::parse_days_time(bytes, offset)
+                } else {
+                    Self::parse_time(bytes, offset, config)
+                }
+            }
         }?;
         d.positive = positive;
 
@@ -420,6 +423,10 @@ impl Duration {
         })
     }
 
+    fn is_duration_date_format(bytes: &[u8]) -> bool {
+        bytes.iter().any(|&byte| byte == b'd' || byte == b'D')
+    }
+
     fn parse_days_time(bytes: &[u8], offset: usize) -> Result<Self, ParseError> {
         let (day, offset) = match bytes.get(offset).copied() {
             Some(c) => Self::parse_number(bytes, c, offset),
@@ -498,16 +505,63 @@ impl Duration {
     }
 
     fn parse_time(bytes: &[u8], offset: usize, config: &TimeConfig) -> Result<Self, ParseError> {
-        let t = crate::time::PureTime::parse(bytes, offset, config)?;
+        let byte_len = bytes.len();
+        if byte_len - offset < 5 {
+            return Err(ParseError::TooShort);
+        }
+        const HOUR_NUMERIC_LIMIT: i64 = 24 * 10i64.pow(8);
+        let mut hour: i64 = 0;
+
+        let mut chunks = bytes
+            .get(offset..)
+            .ok_or(ParseError::TooShort)?
+            .splitn(2, |&byte| byte == b':');
+
+        // can just use `.split_once()` in future maybe, if that stabilises
+        let (hour_part, mut remaining) = match (chunks.next(), chunks.next(), chunks.next()) {
+            (_, _, Some(_)) | (None, _, _) => unreachable!("should always be 1 or 2 chunks"),
+            (Some(_hour_part), None, _) => return Err(ParseError::InvalidCharHour),
+            (Some(hour_part), Some(remaining), None) => (hour_part, remaining),
+        };
+
+        // > 9.999.999.999
+        if hour_part.len() > 10 {
+            return Err(ParseError::DurationHourValueTooLarge);
+        }
 
-        if bytes.len() > t.position {
+        for byte in hour_part {
+            let h = *byte - b'0';
+            if h > 9 {
+                return Err(ParseError::InvalidCharHour);
+            }
+            hour = (hour * 10) + (h as i64);
+        }
+        if hour > HOUR_NUMERIC_LIMIT {
+            return Err(ParseError::DurationHourValueTooLarge);
+        }
+
+        let mut new_bytes = *b"00:00:00.000000";
+        if 3 + remaining.len() > new_bytes.len() {
+            match config.microseconds_precision_overflow_behavior {
+                crate::MicrosecondsPrecisionOverflowBehavior::Truncate => remaining = &remaining[..new_bytes.len() - 3],
+                crate::MicrosecondsPrecisionOverflowBehavior::Error => return Err(ParseError::SecondFractionTooLong),
+            }
+        }
+        let new_bytes = &mut new_bytes[..3 + remaining.len()];
+        new_bytes[3..].copy_from_slice(remaining);
+
+        let t = crate::time::PureTime::parse(new_bytes, 0, config)?;
+
+        if new_bytes.len() > t.position {
             return Err(ParseError::ExtraCharacters);
         }
+        let day = hour as u32 / 24;
+        hour %= 24;
 
         Ok(Self {
             positive: false, // is set above
-            day: 0,
-            second: t.total_seconds(),
+            day,
+            second: t.total_seconds() + (hour as u32) * 3_600,
             microsecond: t.microsecond,
         })
     }
diff --git a/src/lib.rs b/src/lib.rs
index 5017613..dcbc06a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -133,6 +133,8 @@ pub enum ParseError {
     /// a numeric value in the duration is too large
     DurationValueTooLarge,
     /// durations may not exceed 999,999,999 days
+    DurationHourValueTooLarge,
+    /// durations hours must less than 1,000,000,000
     DurationDaysTooLarge,
     /// dates before 1600 are not supported as unix timestamps
     DateTooSmall,
diff --git a/tests/main.rs b/tests/main.rs
index 7f43263..f9ecc6c 100644
--- a/tests/main.rs
+++ b/tests/main.rs
@@ -1153,7 +1153,12 @@ param_tests! {
     duration_time_fraction: ok => "00:01:03.123", "PT1M3.123S";
     duration_time_extra: err => "00:01:03.123x", ExtraCharacters;
     duration_time_timezone: err => "00:01:03x", ExtraCharacters;
-    duration_time_invalid_hour: err => "24:01:03", OutOfRangeHour;
+    duration_time_more_than_24_hour: ok => "24:01:03", "P1DT1M3S";
+    duration_time_way_more_than_24_hour: ok => "2400000000:01:03", "P273972Y220DT1M3S";
+    duration_time_way_more_than_24_hour_long_fraction: ok => "2400000000:01:03.654321", "P273972Y220DT1M3.654321S";
+    duration_time_invalid_over_limit_hour: err => "100000000000:01:03", DurationHourValueTooLarge;
+    duration_time_overflow_hour: err => "100000000000000000000000:01:03", DurationHourValueTooLarge;
+    duration_time_invalid_format_hour: err => "1000xxx000:01:03", InvalidCharHour;
     duration_time_invalid_minute: err => "00:60:03", OutOfRangeMinute;
     duration_time_invalid_second: err => "00:00:60", OutOfRangeSecond;
     duration_time_fraction_too_long: err => "00:00:00.1234567", SecondFractionTooLong;