1 files changed, 2 insertions, 0 deletions
diff --git a/bignum.c b/bignum.c
index 8a6e54a9da..937d5ba8f4 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1248,4 +1248,6 @@ Init_Bignum()
     rb_define_method(cBignum, "to_f", big_to_f, 0);
     rb_define_method(cBignum, "abs", big_abs, 0);
     rb_define_method(cBignum, "size", big_size, 0);
+
+    FL_SET(cBignum, FL_PRIMITIVE);
 }