diff --git a/tools/mrbc/mrbc.c b/tools/mrbc/mrbc.c
index 6d9c85fa9..5a92cd479 100644
--- a/tools/mrbc/mrbc.c
+++ b/tools/mrbc/mrbc.c
@@ -226,7 +226,9 @@ mrb_init_mrblib(mrb_state *mrb)
 {
 }
 
+#ifdef ENABLE_GEMS
 void
 mrb_init_mrbgems(mrb_state *mrb)
 {
 }
+#endif