diff --git a/Simulation/FastSimulation/FastChainPileup/src/MultiParticleGunPileup.cxx b/Simulation/FastSimulation/FastChainPileup/src/MultiParticleGunPileup.cxx
index f3c08335b56483c85ff158b1de27d464892019d0..ccddaa183920ee0ed9303be310edc74de09969fa 100644
--- a/Simulation/FastSimulation/FastChainPileup/src/MultiParticleGunPileup.cxx
+++ b/Simulation/FastSimulation/FastChainPileup/src/MultiParticleGunPileup.cxx
@@ -7,9 +7,11 @@
 // Richard Hawkings, started 20/2/15, + contributions from Vladimir Lyubushkin
 
 #include <algorithm>
+#include <numeric>
 #include <functional>
 #include <iterator>
 
+
 #include "CLHEP/Random/RandPoisson.h"
 #include "FastChainPileup/MultiParticleGunPileup.h"
 
diff --git a/Simulation/FastSimulation/FastChainPileup/src/MultiPy8Pileup.cxx b/Simulation/FastSimulation/FastChainPileup/src/MultiPy8Pileup.cxx
index 1185a9964542e4e75e19da863c2d35a651c5d2ea..35cfe3374d8101628cf7ccb381911da18eb33c84 100644
--- a/Simulation/FastSimulation/FastChainPileup/src/MultiPy8Pileup.cxx
+++ b/Simulation/FastSimulation/FastChainPileup/src/MultiPy8Pileup.cxx
@@ -7,6 +7,7 @@
 // Richard Hawkings, started 20/2/15, + contributions from Vladimir Lyubushkin
 
 #include <algorithm>
+#include <numeric>
 #include <functional>
 #include <iterator>