diff --git a/scrapy/commands/parse.py b/scrapy/commands/parse.py
index d5abe5930..1cefed106 100644
--- a/scrapy/commands/parse.py
+++ b/scrapy/commands/parse.py
@@ -146,9 +146,8 @@ class Command(ScrapyCommand):
             if not self.spidercls:
                 logger.error('Unable to find spider for: %(url)s', {'url': url})
 
-        # Request requires callback argument as callable or None, not string
         def _start_requests(spider):
-            yield self.prepare_request(spider, Request(url, None), opts)
+            yield self.prepare_request(spider, Request(url), opts)
         self.spidercls.start_requests = _start_requests
 
     def start_parsing(self, url, opts):