diff --git a/src/Pstream/mpi/UIPread.C b/src/Pstream/mpi/UIPread.C
index 6994db9395..e7a4b2eb3b 100644
--- a/src/Pstream/mpi/UIPread.C
+++ b/src/Pstream/mpi/UIPread.C
@@ -261,7 +261,7 @@ Foam::label Foam::UIPstream::read
             (
                 buf,
                 bufSize,
-                MPI_PACKED,
+                MPI_BYTE,
                 fromProcNo,
                 tag,
                 PstreamGlobals::MPICommunicators_[communicator],
@@ -317,7 +317,7 @@ Foam::label Foam::UIPstream::read
             (
                 buf,
                 bufSize,
-                MPI_PACKED,
+                MPI_BYTE,
                 fromProcNo,
                 tag,
                 PstreamGlobals::MPICommunicators_[communicator],
diff --git a/src/Pstream/mpi/UOPwrite.C b/src/Pstream/mpi/UOPwrite.C
index 275c2eca43..4ff80f9da6 100644
--- a/src/Pstream/mpi/UOPwrite.C
+++ b/src/Pstream/mpi/UOPwrite.C
@@ -74,7 +74,7 @@ bool Foam::UOPstream::write
         (
             const_cast<char*>(buf),
             bufSize,
-            MPI_PACKED,
+            MPI_BYTE,
             toProcNo,   //procID(toProcNo),
             tag,
             PstreamGlobals::MPICommunicators_[communicator] //MPI_COMM_WORLD
@@ -94,7 +94,7 @@ bool Foam::UOPstream::write
         (
             const_cast<char*>(buf),
             bufSize,
-            MPI_PACKED,
+            MPI_BYTE,
             toProcNo,   //procID(toProcNo),
             tag,
             PstreamGlobals::MPICommunicators_[communicator] //MPI_COMM_WORLD
@@ -116,7 +116,7 @@ bool Foam::UOPstream::write
         (
             const_cast<char*>(buf),
             bufSize,
-            MPI_PACKED,
+            MPI_BYTE,
             toProcNo,   //procID(toProcNo),
             tag,
             PstreamGlobals::MPICommunicators_[communicator],//MPI_COMM_WORLD,