diff --git a/doc/guides/mrbconf.md b/doc/guides/mrbconf.md
index d369020f2..a2546f2ba 100644
--- a/doc/guides/mrbconf.md
+++ b/doc/guides/mrbconf.md
@@ -244,7 +244,3 @@ end
 `MRB_USE_VM_SWITCH_DISPATCH`
 
 - Turn on switch dispatch in VM loop
-
-`MRB_NO_GEMS`
-
-- Disable mgem usage