diff --git a/Source/NSNumber.m b/Source/NSNumber.m
index 88b21af94..a36f5996a 100644
--- a/Source/NSNumber.m
+++ b/Source/NSNumber.m
@@ -356,7 +356,7 @@ static BOOL useSmallInt;
 @implementation NSSmallInt
 #undef VALUE
 #define VALUE (((intptr_t)self) >> OBJC_SMALL_OBJECT_SHIFT)
-#define FORMAT @"%d"
+#define FORMAT @"%" PRIdPTR
 #include "NSNumberMethods.h"
 + (void)load
 {