diff --git a/ext/redcarpet/rc_markdown.c b/ext/redcarpet/rc_markdown.c
index 905148e7..df016fbb 100644
--- a/ext/redcarpet/rc_markdown.c
+++ b/ext/redcarpet/rc_markdown.c
@@ -115,8 +115,8 @@ static VALUE rb_redcarpet_md__new(int argc, VALUE *argv, VALUE klass)
 
 	/* Merge the current options in the @options hash */
 	if (hash != Qnil) {
-		rndr_options = rb_iv_get(rb_rndr, "@options");
-		rb_funcall(rndr_options, rb_intern("merge!"), 1, hash);
+		rndr_options = rb_funcall(rb_iv_get(rb_rndr, "@options"), rb_intern("merge"), 1, hash);
+		rb_iv_set(rb_rndr, "@options", rndr_options);
 	}
 
 	markdown = sd_markdown_new(extensions, 16, &rndr->callbacks, &rndr->options);
diff --git a/test/custom_render_test.rb b/test/custom_render_test.rb
index 61e2256a..5f73c085 100644
--- a/test/custom_render_test.rb
+++ b/test/custom_render_test.rb
@@ -23,7 +23,7 @@ def test_simple_overload
   end
 
   def test_renderer_options
-    parser = Redcarpet::Markdown.new(SimpleRender.new(with_toc_data: true))
+    parser = Redcarpet::Markdown.new(SimpleRender.new({ with_toc_data: true }.freeze), {})
     output = parser.render("# A title")
 
     assert_match "My little poney", output