diff --git a/racket/src/racket/gc2/gc2.h b/racket/src/racket/gc2/gc2.h
index 887ff56c6d..b28f2107f2 100644
--- a/racket/src/racket/gc2/gc2.h
+++ b/racket/src/racket/gc2/gc2.h
@@ -584,7 +584,7 @@ GC2_EXTERN void GC_set_backpointer_object(void *p);
 #endif
 
 /* Macros (implementation-specific): */
-#if defined(__x86_64__) || defined(_WIN64)
+#ifdef SIXTY_FOUR_BIT_INTEGERS
 # define gcLOG_WORD_SIZE 3
 #else
 # define gcLOG_WORD_SIZE 2