diff --git a/imemo.c b/imemo.c
index 8b3018523f..d949466a77 100644
--- a/imemo.c
+++ b/imemo.c
@@ -94,8 +94,9 @@ rb_free_tmp_buffer(volatile VALUE *store)
     rb_imemo_tmpbuf_t *s = (rb_imemo_tmpbuf_t*)ATOMIC_VALUE_EXCHANGE(*store, 0);
     if (s) {
         void *ptr = ATOMIC_PTR_EXCHANGE(s->ptr, 0);
+        long cnt = s->cnt;
         s->cnt = 0;
-        ruby_xfree(ptr);
+        ruby_sized_xfree(ptr, sizeof(VALUE) * cnt);
     }
 }