diff --git a/Calo/CaloAssociators/src/CaloDigitLinker.cpp b/Calo/CaloAssociators/src/CaloDigitLinker.cpp
index dc27dc1acc56ffa1666db29bda8bc438a3581968..f8466d1852b38c8e63a92637aef2d7bdd80a50d8 100644
--- a/Calo/CaloAssociators/src/CaloDigitLinker.cpp
+++ b/Calo/CaloAssociators/src/CaloDigitLinker.cpp
@@ -116,27 +116,29 @@ namespace LHCb::Calo::Algorithm {
       // Make a map of the MC hits/particles and weights.
       std::map<const LHCb::MCCaloHit*, double>  hitMap;
       std::map<const LHCb::MCParticle*, double> particleMap;
-
+      
       for ( auto hit : hits ) {
-
         if ( hit.data() == static_cast<LHCb::MCCaloHit*>( nullptr ) )
           continue; // spillover MCHit contributed to this digit
-
+	
         hitMap[hit] += hit.data()->activeE();
-        particleMap[hit.data()->particle()] += hit.data()->activeE();
-
-        const LHCb::MCParticle* particle = hit.data()->particle();
-
+	auto* mcp = hit.data()->particle();
+	if ( !mcp ) continue;
+	particleMap[mcp] += hit.data()->activeE();
+	
         // Add the energy deposition from the given particle to ALL parents
-        while ( 0 != particle ) {
-          const LHCb::MCVertex* vertex = particle->originVertex();
-          if ( !vertex ) continue;
-          particle = vertex->mother();
-          if ( !particle ) continue;
-          particleMap[particle] += hit.data()->activeE();
-        }
+        const LHCb::MCParticle* particle = mcp;
+	while (true) {
+	  const auto* vtx = particle->originVertex();
+	  if (!vtx) break;
+	  particle = vtx->mother();
+	  if (!particle) break;
+	  
+	  particleMap[particle] += hit.data()->activeE();
+	}
+	
       }
-
+      
       // Make the associations
       hitLinks.link( digit.cellID().index(), hitMap );