diff --git a/src/proxy.c b/src/proxy.c
index 94f0f7f5c99cdb74af784551c8507dee072a0c5a..1a395045bf80aa9940fb0934cc8b04eb6f3764ad 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -42,8 +42,10 @@
 #include "error.h"
 #include "space.h"
 
+#ifdef WITH_MPI
 /* MPI data type for the communications */
 MPI_Datatype pcell_mpi_type;
+#endif
 
 /**
  * @brief Exchange tags between nodes.