diff --git a/src/mem/bus.cc b/src/mem/bus.cc
index 1f96115b8..13e545064 100644
--- a/src/mem/bus.cc
+++ b/src/mem/bus.cc
@@ -605,6 +605,13 @@ Bus::drain(Event * de)
     }
 }
 
+void
+Bus::startup()
+{
+    if (tickNextIdle < curTick)
+        tickNextIdle = (curTick / clock) * clock + clock;
+}
+
 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bus)
 
     Param<int> bus_id;
diff --git a/src/mem/bus.hh b/src/mem/bus.hh
index 5dd98c07e..ee647e20a 100644
--- a/src/mem/bus.hh
+++ b/src/mem/bus.hh
@@ -267,6 +267,7 @@ class Bus : public MemObject
     virtual void deletePortRefs(Port *p);
 
     virtual void init();
+    virtual void startup();
 
     unsigned int drain(Event *de);