diff --git a/trainer.h b/trainer.h
index 3e6b542d6563e7db94134b0ee479bf1f42a1e78c..1b2678218145ff831a718f226fff99e67704b84f 100644
--- a/trainer.h
+++ b/trainer.h
@@ -52,7 +52,9 @@ class Trainer {
     }
 
 };
+
 #ifdef TADAH_BUILD_MPI
+#include <mpi.h>
 extern "C" void blacs_get_(int*, int*, int*);
 extern "C" void blacs_pinfo_(int*, int*);
 extern "C" void blacs_gridinit_(int*, char*, int*, int*);