Index: Objects/stringlib/formatter.h
===================================================================
--- Objects/stringlib/formatter.h	(revision 57624)
+++ Objects/stringlib/formatter.h	(working copy)
@@ -685,7 +685,7 @@
     /* cast "type", because if we're in unicode we need to pass a
        8-bit char.  this is safe, because we've restricted what "type"
        can be */
-    PyOS_snprintf(fmt, sizeof(fmt), "%%.%zd%c", precision, (char)type);
+    PyOS_snprintf(fmt, sizeof(fmt), "%%.%" PY_FORMAT_SIZE_T "d%c", precision, (char)type);
 
     /* call the passed in function to do the actual formatting */
     snprintf(charbuf, sizeof(charbuf), fmt, x);