diff -r cb911e1fb3dc Lib/datetime.py
--- a/Lib/datetime.py	Wed Feb 25 18:14:47 2015 +0200
+++ b/Lib/datetime.py	Wed Feb 25 12:16:43 2015 -0500
@@ -515,8 +515,9 @@
                              self._seconds * other,
                              self._microseconds * other)
         if isinstance(other, float):
+            ms = timedelta(microseconds=1)
             a, b = other.as_integer_ratio()
-            return self * a / b
+            return timedelta(microseconds=self // ms * a / b)
         return NotImplemented
 
     __rmul__ = __mul__