diff --git a/demo/multiple_simulations/src/multiple_simulations.h b/demo/multiple_simulations/src/multiple_simulations.h
index 3d2b30eb1..4084679f9 100644
--- a/demo/multiple_simulations/src/multiple_simulations.h
+++ b/demo/multiple_simulations/src/multiple_simulations.h
@@ -17,6 +17,7 @@
 
 #include <vector>
 #include "biodynamo.h"
+#include "core/behavior/behavior.h"
 
 namespace bdm {