diff --git a/scan_engine.cc b/scan_engine.cc
index f8cf9bad6..1ef80a7f0 100644
--- a/scan_engine.cc
+++ b/scan_engine.cc
@@ -4203,7 +4203,7 @@ static bool do_one_select_round(UltraScanInfo *USI, struct timeval *stime) {
 
     std::list<UltraProbe *>::iterator nextProbeI;
     for (std::list<UltraProbe *>::iterator probeI = host->probes_outstanding.begin(), end = host->probes_outstanding.end();
-        probeI != end && numGoodSD < selectres; probeI = nextProbeI) {
+        probeI != end && numGoodSD < selectres && host->num_probes_outstanding() > 0; probeI = nextProbeI) {
       /* handleConnectResult may remove the probe at probeI, which invalidates
        * the iterator. We copy and increment it here instead of in the for-loop
        * statement to avoid incrementing an invalid iterator */