diff --git a/dis/src/pythia_dis.cc b/dis/src/pythia_dis.cc
index 6736f49f690f78bc83bd5f4c01649631f0139661..b36c5c161f07b3e010698e915a38543ecfd1d5da 100644
--- a/dis/src/pythia_dis.cc
+++ b/dis/src/pythia_dis.cc
@@ -1,6 +1,7 @@
 #include "Pythia8/Pythia.h"
 #include "Pythia8Plugins/HepMC3.h"
 #include <unistd.h>
+#include <cassert>
 
 using namespace Pythia8;