diff --git a/HeavyFlavorAnalysis/RecoDecay/src/BPHDecayVertex.cc b/HeavyFlavorAnalysis/RecoDecay/src/BPHDecayVertex.cc
index 97038181883e0..415b5a7bc37c8 100644
--- a/HeavyFlavorAnalysis/RecoDecay/src/BPHDecayVertex.cc
+++ b/HeavyFlavorAnalysis/RecoDecay/src/BPHDecayVertex.cc
@@ -164,7 +164,7 @@ reco::TransientTrack* BPHDecayVertex::getTransientTrack(const reco::Candidate* c
 const BPHEventSetupWrapper* BPHDecayVertex::getEventSetup() const { return evSetup; }
 
 const string& BPHDecayVertex::getTrackSearchList(const reco::Candidate* cand) const {
-  static string dum = "";
+  static const string dum = "";
   map<const reco::Candidate*, string>::const_iterator iter = searchMap.find(cand);
   if (iter != searchMap.end())
     return iter->second;