Remove unnecessary comma
diff --git a/scrapy/resolver.py b/scrapy/resolver.py
index 554a3a14dba..f69894b1e4e 100644
--- a/scrapy/resolver.py
+++ b/scrapy/resolver.py
@@ -29,7 +29,7 @@ def from_crawler(cls, crawler, reactor):
             cache_size = 0
         return cls(reactor, cache_size, crawler.settings.getfloat('DNS_TIMEOUT'))
 
-    def install_on_reactor(self,):
+    def install_on_reactor(self):
         self.reactor.installResolver(self)
 
     def getHostByName(self, name, timeout=None):
