diff --git a/ruby.c b/ruby.c
index 541ef88..a47d7ce 100644
--- a/ruby.c
+++ b/ruby.c
@@ -111,6 +111,7 @@ cmdline_options_init(struct cmdline_options *opt)
     opt->src.enc.index = src_encoding_index;
     opt->ext.enc.index = -1;
     opt->intern.enc.index = -1;
+    opt->disable |= DISABLE_BIT(gems);
     return opt;
 }