1 files changed, 3 insertions, 1 deletions
diff --git a/gc.c b/gc.c
index f52b5fc348..2c49f96363 100644
--- a/gc.c
+++ b/gc.c
@@ -536,8 +536,10 @@ rb_objspace_free(rb_objspace_t *objspace)
 }
 #endif
 
-/* tiny heap size: 16KB */
+#ifndef HEAP_ALIGN_LOG
+/* default tiny heap size: 16KB */
 #define HEAP_ALIGN_LOG 14
+#endif
 #define HEAP_ALIGN (1UL << HEAP_ALIGN_LOG)
 #define HEAP_ALIGN_MASK (~(~0UL << HEAP_ALIGN_LOG))
 #define REQUIRED_SIZE_BY_MALLOC (sizeof(size_t) * 5)