diff --git a/ext/nokogiri/xml_document.c b/ext/nokogiri/xml_document.c
index 348344c244a..f6bc7ac1ceb 100644
--- a/ext/nokogiri/xml_document.c
+++ b/ext/nokogiri/xml_document.c
@@ -468,8 +468,6 @@ static VALUE canonicalize(int argc, VALUE* argv, VALUE self)
   xmlChar **ns;
   long ns_len, i;
 
-  rb_scan_args(argc, argv, "03", &mode, &incl_ns, &with_comments);
-
   xmlDocPtr doc;
   xmlOutputBufferPtr buf;
   xmlC14NIsVisibleCallback cb = NULL;
@@ -478,6 +476,8 @@ static VALUE canonicalize(int argc, VALUE* argv, VALUE self)
   VALUE rb_cStringIO;
   VALUE io;
 
+  rb_scan_args(argc, argv, "03", &mode, &incl_ns, &with_comments);
+
   Data_Get_Struct(self, xmlDoc, doc);
 
   rb_cStringIO = rb_const_get_at(rb_cObject, rb_intern("StringIO"));