diff --git a/src/zapit/src/zapit.cpp b/src/zapit/src/zapit.cpp
index 8158dc9bf..85c041bc7 100644
--- a/src/zapit/src/zapit.cpp
+++ b/src/zapit/src/zapit.cpp
@@ -2292,6 +2292,8 @@ bool CZapitSdtMonitor::Start()
 
 bool CZapitSdtMonitor::Stop()
 {
+	if (!started)
+		return false;
 	started = false;
 	int ret = join();
 	return (ret == 0);