diff --git a/src/msg.rs b/src/msg.rs
index f8717bc..34fad64 100644
--- a/src/msg.rs
+++ b/src/msg.rs
@@ -1,3 +1,7 @@
+use std::ops;
+
+const BILLION: i64 = 1000000000;
+
 #[derive(Serialize,Deserialize,Debug)]
 pub struct Time {
     pub sec: i32,
@@ -8,6 +12,17 @@ impl Time {
     pub fn new() -> Time {
         Time { sec: 0, nsec: 0 }
     }
+
+    pub fn from_nanos(t: i64) -> Time {
+        Time {
+            sec: (t / BILLION) as i32,
+            nsec: (t % BILLION) as i32,
+        }
+    }
+
+    fn nanos(self) -> i64 {
+        self.sec as i64 * BILLION + self.nsec as i64
+    }
 }
 
 #[derive(Serialize,Deserialize,Debug)]
@@ -20,4 +35,101 @@ impl Duration {
     pub fn new() -> Duration {
         Duration { sec: 0, nsec: 0 }
     }
+
+    pub fn from_nanos(t: i64) -> Duration {
+        Duration {
+            sec: (t / BILLION) as i32,
+            nsec: (t % BILLION) as i32,
+        }
+    }
+
+    fn nanos(self) -> i64 {
+        self.sec as i64 * BILLION + self.nsec as i64
+    }
+}
+
+impl ops::Add<Duration> for Time {
+    type Output = Time;
+    fn add(self, rhs: Duration) -> Self::Output {
+        Time::from_nanos(self.nanos() + rhs.nanos())
+    }
+}
+
+impl ops::Add<Duration> for Duration {
+    type Output = Duration;
+    fn add(self, rhs: Duration) -> Self::Output {
+        Duration::from_nanos(self.nanos() + rhs.nanos())
+    }
+}
+
+impl ops::Sub<Time> for Time {
+    type Output = Duration;
+    fn sub(self, rhs: Time) -> Self::Output {
+        Duration::from_nanos(self.nanos() - rhs.nanos())
+    }
+}
+
+impl ops::Sub<Duration> for Time {
+    type Output = Time;
+    fn sub(self, rhs: Duration) -> Self::Output {
+        Time::from_nanos(self.nanos() - rhs.nanos())
+    }
+}
+
+impl ops::Sub<Duration> for Duration {
+    type Output = Duration;
+    fn sub(self, rhs: Duration) -> Self::Output {
+        Duration::from_nanos(self.nanos() - rhs.nanos())
+    }
+}
+
+impl ops::Neg for Duration {
+    type Output = Duration;
+    fn neg(self) -> Self::Output {
+        Duration {
+            sec: -self.sec,
+            nsec: -self.nsec,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{Duration, Time};
+
+    #[test]
+    fn from_nanos_works() {
+        let time = Time::from_nanos(123456789987654321);
+        assert_eq!(time.sec, 123456789);
+        assert_eq!(time.nsec, 987654321);
+        let time = Duration::from_nanos(123456789987654321);
+        assert_eq!(time.sec, 123456789);
+        assert_eq!(time.nsec, 987654321);
+    }
+
+    #[test]
+    fn nanos_works() {
+        let time = Time {
+            sec: 123456789,
+            nsec: 987654321,
+        };
+        assert_eq!(time.nanos(), 123456789987654321);
+        let time = Duration {
+            sec: 123456789,
+            nsec: 987654321,
+        };
+        assert_eq!(time.nanos(), 123456789987654321);
+    }
+
+    #[test]
+    fn works_with_negative() {
+        let time = Time::from_nanos(-123456789987654321);
+        assert_eq!(time.sec, -123456789);
+        assert_eq!(time.nsec, -987654321);
+        assert_eq!(time.nanos(), -123456789987654321);
+        let time = Duration::from_nanos(-123456789987654321);
+        assert_eq!(time.sec, -123456789);
+        assert_eq!(time.nsec, -987654321);
+        assert_eq!(time.nanos(), -123456789987654321);
+    }
 }