diff -r 5e7fc2a42c3c Lib/test/test_time.py
--- a/Lib/test/test_time.py	Thu Mar 31 11:48:31 2011 -0400
+++ b/Lib/test/test_time.py	Sat Apr 02 17:35:00 2011 -0700
@@ -37,6 +37,12 @@
             except ValueError:
                 self.fail('conversion specifier: %r failed.' % format)
 
+        # Issue #10762: Guard against invalid/non-supported format string
+        # so that Python don't crash (Windows crashes when the format string
+        # input to [w]strftime is not kosher.
+        with self.assertRaises(ValueError):
+            time.strftime('%f')
+
     def test_strftime_bounds_checking(self):
         # Make sure that strftime() checks the bounds of the various parts
         #of the time tuple (0 is valid for *all* values).
diff -r 5e7fc2a42c3c Modules/timemodule.c
--- a/Modules/timemodule.c	Thu Mar 31 11:48:31 2011 -0400
+++ b/Modules/timemodule.c	Sat Apr 02 17:35:00 2011 -0700
@@ -487,7 +487,7 @@
         if (outbuf[1]=='#')
             ++outbuf; /* not documented by python, */
         if (outbuf[1]=='\0' ||
-            !strchr("aAbBcdfHIjmMpSUwWxXyYzZ%", outbuf[1]))
+            !strchr("aAbBcdHIjmMpSUwWxXyYzZ%", outbuf[1]))
         {
             PyErr_SetString(PyExc_ValueError, "Invalid format string");
             return 0;