diff --git a/libsrc/core/mpi_wrapper.hpp b/libsrc/core/mpi_wrapper.hpp
index 07b15867..ae3e2c4c 100644
--- a/libsrc/core/mpi_wrapper.hpp
+++ b/libsrc/core/mpi_wrapper.hpp
@@ -6,6 +6,7 @@
 #include <mpi.h>
 #endif
 
+#include "array.hpp"
 #include "exception.hpp"
 
 namespace ngcore