diff --git a/test/monitoring/monitoring_prof.c b/test/monitoring/monitoring_prof.c
index be9e0d8198..946f690a3a 100644
--- a/test/monitoring/monitoring_prof.c
+++ b/test/monitoring/monitoring_prof.c
@@ -4,6 +4,7 @@
  *                         reserved.
  * Copyright (c) 2013-2015 Inria.  All rights reserved.
  * Copyright (c) 2013-2015 Bull SAS.  All rights reserved.
+ * Copyright (c) 2016 Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -36,6 +37,7 @@ writing 4x4 matrix to monitoring_avg.mat
 #include <mpi.h>
 #include <string.h>
 #include <stdint.h>
+#include <inttypes.h>
 
 static MPI_T_pvar_session session;
 static int comm_world_size;
@@ -242,7 +244,7 @@ int write_mat(char * filename, uint64_t * mat, unsigned int dim)
 
     for (i = 0; i < comm_world_size; ++i) {
         for (j = 0; j < comm_world_size; ++j) {
-            fprintf(matrix_file, "%llu ", mat[i * comm_world_size + j]);
+            fprintf(matrix_file, "%" PRIu64 " ", mat[i * comm_world_size + j]);
         }
         fprintf(matrix_file, "\n");
     }