diff --git a/tools/mrbc/mrbc.c b/tools/mrbc/mrbc.c
index e711b69cb..3553fe646 100644
--- a/tools/mrbc/mrbc.c
+++ b/tools/mrbc/mrbc.c
@@ -204,11 +204,6 @@ main(int argc, char **argv)
   return n;
 }
 
-void
-mrb_init_ext(mrb_state *mrb)
-{
-}
-
 void
 mrb_init_mrblib(mrb_state *mrb)
 {