--- Objects/stringobject2.6b1.c	2008-06-10 14:23:22.000000000 -0700
+++ Objects/stringobject.c	2008-06-21 16:32:31.000000000 -0700
@@ -4,6 +4,7 @@
 
 #include "Python.h"
 #include <ctype.h>
+#include <float.h>  /* DBL_DIG */
 
 #ifdef COUNT_ALLOCS
 int null_strings, one_strings;
@@ -200,6 +201,13 @@
 				   This isn't enough for octal. */
 				n += 20;
 				break;
+			case 'f':
+				(void) va_arg(count, double);
+				/* assume %f produces at most DBL_DIG 
+				   digits before and after the decimal
+				   point, plus the latter plus a sign */
+				n += DBL_DIG + 2 + DBL_DIG;
+				break;
 			case 's':
 				s = va_arg(count, char*);
 				n += strlen(s);
@@ -239,17 +247,17 @@
 	for (f = format; *f; f++) {
 		if (*f == '%') {
 			const char* p = f++;
-			Py_ssize_t i;
+			Py_ssize_t i, w;
+			int precision = 0;
 			int longflag = 0;
 			int size_tflag = 0;
-			/* parse the width.precision part (we're only
-			   interested in the precision value, if any) */
-			n = 0;
+			/* parse the width.precision, if any */
+			w = n = 0;
 			while (isdigit(Py_CHARMASK(*f)))
-				n = (n*10) + *f++ - '0';
+				w = (w*10) + *f++ - '0';
 			if (*f == '.') {
+				precision = 1;
 				f++;
-				n = 0;
 				while (isdigit(Py_CHARMASK(*f)))
 					n = (n*10) + *f++ - '0';
 			}
@@ -293,6 +301,16 @@
 						va_arg(vargs, unsigned int));
 				s += strlen(s);
 				break;
+			case 'f':
+				if (precision) {
+					if (n > DBL_DIG)
+						n = DBL_DIG;
+					sprintf(s, "%.*f", (int)n, va_arg(vargs, double));
+				}
+				else
+					sprintf(s, "%f", va_arg(vargs, double));
+				s += strlen(s);
+				break;
 			case 'i':
 				sprintf(s, "%i", va_arg(vargs, int));
 				s += strlen(s);
@@ -306,6 +324,8 @@
 				i = strlen(p);
 				if (n > 0 && i > n)
 					i = n;
+				else if (w > 0 && i > w)
+					i = w;
 				Py_MEMCPY(s, p, i);
 				s += i;
 				break;
@@ -334,7 +354,7 @@
 	}
 
  end:
-	_PyString_Resize(&string, s - PyString_AS_STRING(string));
+	_PyString_Resize(&string, (Py_ssize_t)(s - PyString_AS_STRING(string)));
 	return string;
 }