diff --git a/scrapy/core/engine.py b/scrapy/core/engine.py
index 25284dea9..732721f35 100644
--- a/scrapy/core/engine.py
+++ b/scrapy/core/engine.py
@@ -416,7 +416,7 @@ class ExecutionEngine(object):
             "datetime.now()-self.start_time", 
             "self.is_idle()", 
             "self.scheduler.is_idle()",
-            "len(self.scheduler.pending_domains)",
+            "len(self.scheduler.pending_requests)",
             "self.downloader.is_idle()",
             "len(self.downloader.sites)",
             "self.downloader.has_capacity()",