diff --git a/src/parallel/decompose/ptscotchDecomp/ptscotchDecomp.C b/src/parallel/decompose/ptscotchDecomp/ptscotchDecomp.C
index f57e7d2aac540d6451eb3c92b0c3fc3b6fa639ac..c459252e1cd1f3ae8d2a8004f48147b2e84233d3 100644
--- a/src/parallel/decompose/ptscotchDecomp/ptscotchDecomp.C
+++ b/src/parallel/decompose/ptscotchDecomp/ptscotchDecomp.C
@@ -207,13 +207,11 @@ License
 #include "globalIndex.H"
 #include "SubField.H"
 
-extern "C"
-{
-    #include <stdio.h>
-    #include <mpi.h>
-    #include "ptscotch.h"
-}
+#pragma GCC diagnostic ignored "-Wold-style-cast"
 
+#include <cstdio>
+#include <mpi.h>
+#include "ptscotch.h"
 
 // Hack: scotch generates floating point errors so need to switch of error
 //       trapping!
diff --git a/src/renumber/zoltanRenumber/zoltanRenumber.C b/src/renumber/zoltanRenumber/zoltanRenumber.C
index da7a2957b535fc198f3600ba8330bdca0328cf0a..2d7a744debb90f875dceacfdd5e4f6f5fabeb066 100644
--- a/src/renumber/zoltanRenumber/zoltanRenumber.C
+++ b/src/renumber/zoltanRenumber/zoltanRenumber.C
@@ -57,6 +57,7 @@ SourceFiles
 #include "globalIndex.H"
 #include "uint.H"
 
+#pragma GCC diagnostic ignored "-Wold-style-cast"
 #include "zoltan.h"
 #include <mpi.h>