diff --git a/quickjs.h b/quickjs.h
index adeb2ba..5c7c9e4 100644
--- a/quickjs.h
+++ b/quickjs.h
@@ -55,14 +55,8 @@ typedef struct JSClass JSClass;
 typedef uint32_t JSClassID;
 typedef uint32_t JSAtom;
 
-#if INTPTR_MAX >= INT64_MAX
-#define JS_PTR64
-#define JS_PTR64_DEF(a) a
-#else
-#define JS_PTR64_DEF(a)
-#endif
-
-#ifndef JS_PTR64
+#if INTPTR_MAX < INT64_MAX
+/* Use NAN boxing for 32bit builds. */
 #define JS_NAN_BOXING
 #endif