diff --git a/mrbgems/mruby-bigint/core/bigint.c b/mrbgems/mruby-bigint/core/bigint.c
index d5ff04aa5..fea4782a4 100644
--- a/mrbgems/mruby-bigint/core/bigint.c
+++ b/mrbgems/mruby-bigint/core/bigint.c
@@ -1260,12 +1260,6 @@ mrb_bint_div_ii(mrb_state *mrb, mrb_int x, mrb_int y)
   return bint_norm(mrb, b);
 }
 
-mrb_value
-mrb_bint_idiv(mrb_state *mrb, mrb_value x, mrb_value y)
-{
-  return mrb_nil_value();
-}
-
 mrb_value
 mrb_bint_mod(mrb_state *mrb, mrb_value x, mrb_value y)
 {