diff --git a/src/XrdSys/XrdSysIOEvents.cc b/src/XrdSys/XrdSysIOEvents.cc
index b932d72a8bb..b3d6a0211b5 100644
--- a/src/XrdSys/XrdSysIOEvents.cc
+++ b/src/XrdSys/XrdSysIOEvents.cc
@@ -1018,7 +1018,9 @@ void XrdSys::IOEvents::Poller::Stop()
 
 // First we must stop the poller thread in an orderly fashion.
 //
+   adMutex.UnLock();
    SendCmd(cmdbuff);
+   adMutex.Lock();
 
 // Close the pipe communication mechanism
 //