diff --git a/src/dump.c b/src/dump.c
index 97acf1024..c0ad4b689 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -110,7 +110,7 @@ get_pool_block_size(mrb_state *mrb, const mrb_irep *irep)
 
     switch (irep->pool[pool_no].tt) {
     case IREP_TT_INT64:
-#ifdef MRB_64BIT
+#if defined(MRB_64BIT) || defined(MRB_INT64)
       {
         int64_t i = irep->pool[pool_no].u.i64;
 
@@ -172,8 +172,8 @@ write_pool_block(mrb_state *mrb, const mrb_irep *irep, uint8_t *buf)
     int ai = mrb_gc_arena_save(mrb);
 
     switch (irep->pool[pool_no].tt) {
-#ifdef MRB_64BIT
     case IREP_TT_INT64:
+#if defined(MRB_64BIT) || defined(MRB_INT64)
       {
         int64_t i = irep->pool[pool_no].u.i64;
         if (i < INT32_MIN || INT32_MAX < i) {