diff --git a/scrapy/extensions/memusage.py b/scrapy/extensions/memusage.py
index 34bad8246..322213cf0 100644
--- a/scrapy/extensions/memusage.py
+++ b/scrapy/extensions/memusage.py
@@ -36,7 +36,7 @@ class MemoryUsage(object):
         self.limit = crawler.settings.getint('MEMUSAGE_LIMIT_MB')*1024*1024
         self.warning = crawler.settings.getint('MEMUSAGE_WARNING_MB')*1024*1024
         self.report = crawler.settings.getbool('MEMUSAGE_REPORT')
-        self.check_interval = crawler.settings.getfloat('MEMUSAGE_CHECK_INTERVAL_SECONDS', 60.0)
+        self.check_interval = crawler.settings.getfloat('MEMUSAGE_CHECK_INTERVAL_SECONDS')
         self.mail = MailSender.from_settings(crawler.settings)
         crawler.signals.connect(self.engine_started, signal=signals.engine_started)
         crawler.signals.connect(self.engine_stopped, signal=signals.engine_stopped)
diff --git a/scrapy/settings/default_settings.py b/scrapy/settings/default_settings.py
index 0ea014007..79b6e44f0 100644
--- a/scrapy/settings/default_settings.py
+++ b/scrapy/settings/default_settings.py
@@ -186,6 +186,7 @@ MAIL_USER = None
 MEMDEBUG_ENABLED = False        # enable memory debugging
 MEMDEBUG_NOTIFY = []            # send memory debugging report by mail at engine shutdown
 
+MEMUSAGE_CHECK_INTERVAL_SECONDS = 60.0
 MEMUSAGE_ENABLED = False
 MEMUSAGE_LIMIT_MB = 0
 MEMUSAGE_NOTIFY_MAIL = []