1 files changed, 2 insertions, 0 deletions
diff --git a/internal/imemo.h b/internal/imemo.h
index 68e7e9569a..f52b60e016 100644
--- a/internal/imemo.h
+++ b/internal/imemo.h
@@ -126,7 +126,9 @@ struct MEMO {
    rb_ary_set_len((value), offsetof(type, member) / sizeof(VALUE)), \
    MEMO_FOR(type, value))
 
+#ifndef RUBY_RUBYPARSER_H
 typedef struct rb_imemo_tmpbuf_struct rb_imemo_tmpbuf_t;
+#endif
 rb_imemo_tmpbuf_t *rb_imemo_tmpbuf_parser_heap(void *buf, rb_imemo_tmpbuf_t *old_heap, size_t cnt);
 struct vm_ifunc *rb_vm_ifunc_new(rb_block_call_func_t func, const void *data, int min_argc, int max_argc);
 static inline enum imemo_type imemo_type(VALUE imemo);