diff --git a/asynccp/loop.py b/asynccp/loop.py
index 173656a..e2f347a 100755
--- a/asynccp/loop.py
+++ b/asynccp/loop.py
@@ -59,10 +59,10 @@ class ScheduledTask:
     def change_rate(self, frequency):
         """ Update the task rate to a new frequency. Float hz or asynccp.time.Duration interval """
         if isinstance(frequency, asynccp.time.Duration):
-            hz = frequency.as_frequency()
+            self._nanoseconds_per_invocation = frequency.as_nanoseconds()
         else:
             hz = frequency
-        self._nanoseconds_per_invocation = (1 / hz) * 1000000000
+            self._nanoseconds_per_invocation = 1000000000 / hz
 
     def stop(self):
         """ Stop the task (does not interrupt a currently running task) """
diff --git a/asynccp/time.py b/asynccp/time.py
index 3a2109f..68d79f2 100644
--- a/asynccp/time.py
+++ b/asynccp/time.py
@@ -2,48 +2,48 @@
 class Duration:
     @staticmethod
     def of_hours(count):
-        return Duration(count * 60 * 60 * 1000000)
+        return Duration(count * 60 * 60 * 1000000000)
 
     @staticmethod
     def of_minutes(count):
-        return Duration(count * 60 * 1000000)
+        return Duration(count * 60 * 1000000000)
 
     @staticmethod
     def of_seconds(count):
-        return Duration(count * 1000000)
+        return Duration(count * 1000000000)
 
     @staticmethod
     def of_milliseconds(count):
-        return Duration(count * 1000)
+        return Duration(count * 1000000)
 
     @staticmethod
     def of_microseconds(count):
         return Duration(count)
 
-    def __init__(self, microseconds):
-        self._microseconds = int(microseconds)
+    def __init__(self, nanoseconds):
+        self._nanoseconds = int(nanoseconds)
 
     def __add__(self, other):
-        return Duration(self._microseconds + other._microseconds)
+        return Duration(self._nanoseconds + other._nanoseconds)
 
     def __sub__(self, other):
-        return Duration(self._microseconds - other._microseconds)
+        return Duration(self._nanoseconds - other._nanoseconds)
 
     def __neg__(self):
-        return Duration(-1 * self._microseconds)
+        return Duration(-1 * self._nanoseconds)
 
     def as_frequency(self):
         """returns this duration as a frequency interval in HZ"""
-        return 1000000.0 / self._microseconds
+        return 1000000000.0 / self._nanoseconds
 
     def as_seconds(self):
-        return self._microseconds / 1000000.0
+        return self._nanoseconds / 1000000000.0
 
     def as_milliseconds(self):
-        return self._microseconds / 1000.0
+        return self._nanoseconds / 1000000.0
 
     def as_microseconds(self):
-        return self._microseconds
+        return self._nanoseconds / 1000.0
 
     def as_nanoseconds(self):
-        return self._microseconds * 1000
+        return self._nanoseconds