Index: Modules/datetimemodule.c
===================================================================
--- Modules/datetimemodule.c	(revision 58132)
+++ Modules/datetimemodule.c	(working copy)
@@ -1177,6 +1177,15 @@
 	return NULL;
 }
 
+static PyObject *
+make_freplacement(PyObject *object)
+{
+	char freplacement[7];
+	sprintf(freplacement, "%06d", TIME_GET_MICROSECOND(object));
+
+	return PyBytes_FromStringAndSize(freplacement, strlen(freplacement));
+}
+
 /* I sure don't want to reproduce the strftime code from the time module,
  * so this imports the module and calls it.  All the hair is due to
  * giving special meanings to the %z and %Z format codes via a preprocessing
@@ -1192,6 +1201,7 @@
 
 	PyObject *zreplacement = NULL;	/* py string, replacement for %z */
 	PyObject *Zreplacement = NULL;	/* py string, replacement for %Z */
+	PyObject *freplacement = NULL;	/* py string, replacement for %f */
 
 	const char *pin;/* pointer to next char in input format */
         Py_ssize_t flen;/* length of input format */
@@ -1243,7 +1253,7 @@
 	 * a new format.  Since computing the replacements for those codes
 	 * is expensive, don't unless they're actually used.
 	 */
-	totalnew = flen + 1;	/* realistic if no %z/%Z */
+	totalnew = flen + 1;	/* realistic if no %z/%Z/%f */
 	newfmt = PyBytes_FromStringAndSize(NULL, totalnew);
 	if (newfmt == NULL) goto Done;
 	pnew = PyBytes_AsString(newfmt);
@@ -1301,6 +1311,18 @@
 			ptoappend = PyBytes_AS_STRING(Zreplacement);
 			ntoappend = PyBytes_GET_SIZE(Zreplacement);
 		}
+		else if (ch == 'f') {
+			/* format microseconds */
+			if (freplacement == NULL) {
+				freplacement = make_freplacement(object);
+				if (freplacement == NULL)
+					goto Done;
+			}
+			assert(freplacement != NULL);
+			assert(PyBytes_Check(freplacement));
+			ptoappend = PyBytes_AS_STRING(freplacement);
+			ntoappend = PyBytes_GET_SIZE(freplacement);
+		}
 		else {
 			/* percent followed by neither z nor Z */
 			ptoappend = pin - 2;
@@ -1347,6 +1369,7 @@
 		Py_DECREF(time);
     	}
  Done:
+	Py_XDECREF(freplacement);
 	Py_XDECREF(zreplacement);
 	Py_XDECREF(Zreplacement);
 	Py_XDECREF(newfmt);
@@ -3159,7 +3182,7 @@
 {
 	char buf[100];
 	PyObject *result;
-	int us = TIME_GET_MICROSECOND(self);;
+	int us = TIME_GET_MICROSECOND(self);
 
 	if (us)
 		result = PyUnicode_FromFormat("%02d:%02d:%02d.%06d",