diff --git a/persistent/_timestamp.c b/persistent/_timestamp.c
index 56c3230..3b8bb35 100644
--- a/persistent/_timestamp.c
+++ b/persistent/_timestamp.c
@@ -202,15 +202,6 @@ TimeStamp_sec(TimeStamp *self)
     v = (self->data[4] * 16777216 + self->data[5] * 65536
      + self->data[6] * 256 + self->data[7]);
     sec = SCONV * (double)v;
-    /* always round to 6 places for consistency with the Python version.
-       We really only record that level of precision anyway. */
-#if defined(_MSC_VER) && _MSC_VER <= 1600
-    /* the windows compilers for Python 2.7 and 3.4 don't support C99
-    round(). 1600 is visual studio 10, aka 2010, used for 3.4 */
-    sec = floor((sec * 1000000.0) + 0.5) / 1000000.0;
-#else
-    sec = round(sec * 1000000.0) / 1000000.0;
-#endif
     return sec;
 }
 
diff --git a/persistent/timestamp.py b/persistent/timestamp.py
index cd99cbd..a031a72 100644
--- a/persistent/timestamp.py
+++ b/persistent/timestamp.py
@@ -53,6 +53,7 @@ def fromutc(self, dt):
         return dt
 
 def _makeUTC(y, mo, d, h, mi, s):
+    s = round(s, 6) # microsecond precision, to match the C implementation
     usec, sec = math.modf(s)
     sec = int(sec)
     usec = int(usec * 1e6)
@@ -75,7 +76,7 @@ def _parseRaw(octets):
     day = a // (60 * 24) % 31 + 1
     month = a // (60 * 24 * 31) % 12 + 1
     year = a // (60 * 24 * 31 * 12) + 1900
-    second = round(b * _SCONV, 6) #microsecond precision
+    second = b * _SCONV
     return (year, month, day, hour, minute, second)