diff -aruN nspr-4.8.6/mozilla/nsprpub/pr/include/prprf.h nspr-4.8.6.N/mozilla/nsprpub/pr/include/prprf.h
--- nspr-4.8.6/mozilla/nsprpub/pr/include/prprf.h	2004-04-25 08:00:47.000000000 -0700
+++ nspr-4.8.6.N/mozilla/nsprpub/pr/include/prprf.h	2015-05-08 11:15:40.200961412 -0700
@@ -48,6 +48,8 @@
 **	%hd, %hu, %hx, %hX, %ho - 16-bit versions of above
 **	%ld, %lu, %lx, %lX, %lo - 32-bit versions of above
 **	%lld, %llu, %llx, %llX, %llo - 64 bit versions of above
+**	%td, %tu, %tx, %tX, %to - PRPtrdiff versions of the above (deals with machine dependent PRPtrdiff size)
+**	%zd, %zu, %zx, %zX, %zo - PRSize versions of above (deals with machine dependent PRSize size)
 **	%s - string
 **	%c - character
 **	%p - pointer (deals with machine dependent pointer size)
diff -aruN nspr-4.8.6/mozilla/nsprpub/pr/src/io/prprf.c nspr-4.8.6.N/mozilla/nsprpub/pr/src/io/prprf.c
--- nspr-4.8.6/mozilla/nsprpub/pr/src/io/prprf.c	2008-05-31 08:10:17.000000000 -0700
+++ nspr-4.8.6.N/mozilla/nsprpub/pr/src/io/prprf.c	2015-05-08 11:12:46.305410769 -0700
@@ -820,6 +820,28 @@
 		type = TYPE_INT64;
 		c = *fmt++;
 	    }
+	} else if (c == 't') {
+		if (sizeof(PRPtrdiff) == sizeof(PRInt32)) {
+		    type = TYPE_UINT32;
+		} else if (sizeof(PRPtrdiff) == sizeof(PRInt64)) {
+		    type = TYPE_UINT64;
+		} else if (sizeof(PRPtrdiff) == sizeof(PRIntn)) {
+		    type = TYPE_UINTN;
+		} else {
+		    PR_ASSERT(0);
+		}
+		c = *fmt++;
+	} else if (c == 'z') {
+		if (sizeof(PRSize) == sizeof(PRInt32)) {
+		    type = TYPE_UINT32;
+		} else if (sizeof(PRSize) == sizeof(PRInt64)) {
+		    type = TYPE_UINT64;
+		} else if (sizeof(PRSize) == sizeof(PRIntn)) {
+		    type = TYPE_UINTN;
+		} else {
+		    PR_ASSERT(0);
+		}
+		c = *fmt++;
 	}
 
 	/* format */