diff --git a/retroshare-gui/src/gui/statistics/RttStatistics.cpp b/retroshare-gui/src/gui/statistics/RttStatistics.cpp
index f4e97948e..3221e49ee 100644
--- a/retroshare-gui/src/gui/statistics/RttStatistics.cpp
+++ b/retroshare-gui/src/gui/statistics/RttStatistics.cpp
@@ -104,13 +104,12 @@ void RttGraphSource::getValues(std::map<std::string,float>& vals) const
     rsPeers->getOnlineList(idList);
 
     vals.clear() ;
-    std::list<RsRttPongResult> results ;
-
     for(std::list<RsPeerId>::const_iterator it(idList.begin());it!=idList.end();++it)
     {
-        rsRtt->getPongResults(*it, 1, results);
-
-    vals[(*it).toStdString()] = results.back().mRTT ;
+        std::list<RsRttPongResult> results ;
+        if (rsRtt->getPongResults(*it, 1, results) > 0 && !results.empty()) {
+            vals[(*it).toStdString()] = results.back().mRTT ;
+        }
     }
 }