diff --git a/src/Pstream/Allwclean b/src/Pstream/Allwclean
index c6b20903e8..fa3f2b327a 100755
--- a/src/Pstream/Allwclean
+++ b/src/Pstream/Allwclean
@@ -1,11 +1,10 @@
 #!/bin/sh
 cd "${0%/*}" || exit                                # Run from this directory
-. ${WM_PROJECT_DIR:?}/wmake/scripts/wmakeFunctions  # Require wmake functions
 
 #------------------------------------------------------------------------------
 
 wclean dummy
 
-wcleanLibMpi mpi
+./Allwclean-mpi
 
 #------------------------------------------------------------------------------
diff --git a/src/Pstream/Allwclean-mpi b/src/Pstream/Allwclean-mpi
new file mode 100755
index 0000000000..d238e435a1
--- /dev/null
+++ b/src/Pstream/Allwclean-mpi
@@ -0,0 +1,9 @@
+#!/bin/sh
+cd "${0%/*}" || exit                                # Run from this directory
+. ${WM_PROJECT_DIR:?}/wmake/scripts/wmakeFunctions  # Require wmake functions
+
+#------------------------------------------------------------------------------
+
+wcleanLibMpi mpi
+
+#------------------------------------------------------------------------------
diff --git a/src/Pstream/Allwmake b/src/Pstream/Allwmake
index 7c89339442..dd2ad10d8a 100755
--- a/src/Pstream/Allwmake
+++ b/src/Pstream/Allwmake
@@ -1,13 +1,12 @@
 #!/bin/sh
 cd "${0%/*}" || exit                                # Run from this directory
 . ${WM_PROJECT_DIR:?}/wmake/scripts/AllwmakeParseArguments
-. ${WM_PROJECT_DIR:?}/wmake/scripts/wmakeFunctions  # Require wmake functions
 
 #------------------------------------------------------------------------------
 
 echo "wmake $targetType dummy (mpi=$WM_MPLIB)"
 wmake $targetType dummy
 
-wmakeLibMpi mpi
+./Allwmake-mpi $targetType $*
 
 #------------------------------------------------------------------------------
diff --git a/src/Pstream/Allwmake-mpi b/src/Pstream/Allwmake-mpi
new file mode 100755
index 0000000000..bc36b8cc32
--- /dev/null
+++ b/src/Pstream/Allwmake-mpi
@@ -0,0 +1,13 @@
+#!/bin/sh
+cd "${0%/*}" || exit                                # Run from this directory
+# No AllwmakeParseArguments [infinite loop via Allwmake]
+. ${WM_PROJECT_DIR:?}/wmake/scripts/wmake.wmake-args
+. ${WM_PROJECT_DIR:?}/wmake/scripts/wmakeFunctions  # Require wmake functions
+
+#------------------------------------------------------------------------------
+# Environment
+#   - FOAM_MPI_LIBBIN (optional: defaults to FOAM_LIBBIN/FOAM_MPI)
+
+wmakeLibMpi mpi
+
+#------------------------------------------------------------------------------
diff --git a/src/Pstream/mpi/Make/files b/src/Pstream/mpi/Make/files
index c01382d678..eccdf77664 100644
--- a/src/Pstream/mpi/Make/files
+++ b/src/Pstream/mpi/Make/files
@@ -3,4 +3,4 @@ UIPread.C
 UPstream.C
 PstreamGlobals.C
 
-LIB = $(FOAM_LIBBIN)/$(FOAM_MPI)/libPstream
+LIB = $(FOAM_MPI_LIBBIN)/libPstream
diff --git a/src/Pstream/mpi/Make/options b/src/Pstream/mpi/Make/options
index e255c81d10..7d010be785 100644
--- a/src/Pstream/mpi/Make/options
+++ b/src/Pstream/mpi/Make/options
@@ -1,6 +1,11 @@
 sinclude $(GENERAL_RULES)/mplib$(WM_MPLIB)
 sinclude $(DEFAULT_RULES)/mplib$(WM_MPLIB)
 
+/* Default is PROJECT LIB/mpi target */
+ifeq (,$(FOAM_MPI_LIBBIN))
+    FOAM_MPI_LIBBIN := $(FOAM_LIBBIN)/$(FOAM_MPI)
+endif
+
 EXE_INC  = $(PFLAGS) $(PINC) $(c++LESSWARN)
 
 LIB_LIBS = $(PLIBS)
diff --git a/src/parallel/decompose/Allwclean b/src/parallel/decompose/Allwclean
index a9d95a9efe..e6b78d10c6 100755
--- a/src/parallel/decompose/Allwclean
+++ b/src/parallel/decompose/Allwclean
@@ -1,6 +1,5 @@
 #!/bin/sh
 cd "${0%/*}" || exit                                # Run from this directory
-. ${WM_PROJECT_DIR:?}/wmake/scripts/wmakeFunctions  # Require wmake functions
 
 #------------------------------------------------------------------------------
 
@@ -10,6 +9,6 @@ wclean scotchDecomp
 wclean decompositionMethods
 wclean decompose
 
-wcleanLibMpi ptscotchDecomp
+./Allwclean-mpi
 
 #------------------------------------------------------------------------------
diff --git a/src/parallel/decompose/Allwclean-mpi b/src/parallel/decompose/Allwclean-mpi
new file mode 100755
index 0000000000..2ae2186dc4
--- /dev/null
+++ b/src/parallel/decompose/Allwclean-mpi
@@ -0,0 +1,9 @@
+#!/bin/sh
+cd "${0%/*}" || exit                                # Run from this directory
+. ${WM_PROJECT_DIR:?}/wmake/scripts/wmakeFunctions  # Require wmake functions
+
+#------------------------------------------------------------------------------
+
+wcleanLibMpi ptscotchDecomp
+
+#------------------------------------------------------------------------------
diff --git a/src/parallel/decompose/Allwmake b/src/parallel/decompose/Allwmake
index ad5d2931e6..c9bc6b610a 100755
--- a/src/parallel/decompose/Allwmake
+++ b/src/parallel/decompose/Allwmake
@@ -1,7 +1,6 @@
 #!/bin/sh
 cd "${0%/*}" || exit                                # Run from this directory
 . ${WM_PROJECT_DIR:?}/wmake/scripts/AllwmakeParseArguments
-. ${WM_PROJECT_DIR:?}/wmake/scripts/wmakeFunctions  # Require wmake functions
 . ${WM_PROJECT_DIR:?}/wmake/scripts/have_kahip
 . ${WM_PROJECT_DIR:?}/wmake/scripts/have_metis
 . ${WM_PROJECT_DIR:?}/wmake/scripts/have_scotch
@@ -27,12 +26,8 @@ fi
 if have_scotch
 then
     wmake $targetType scotchDecomp
-
-    if have_ptscotch
-    then
-        wmakeLibMpi ptscotchDecomp "scotch=$SCOTCH_VERSION"
-    fi
 fi
 
+./Allwmake-mpi $targetType $*
 
 #------------------------------------------------------------------------------
diff --git a/src/parallel/decompose/Allwmake-mpi b/src/parallel/decompose/Allwmake-mpi
new file mode 100755
index 0000000000..6d89dc5179
--- /dev/null
+++ b/src/parallel/decompose/Allwmake-mpi
@@ -0,0 +1,24 @@
+#!/bin/sh
+cd "${0%/*}" || exit                                # Run from this directory
+# No AllwmakeParseArguments [infinite loop via Allwmake]
+. ${WM_PROJECT_DIR:?}/wmake/scripts/wmake.wmake-args
+. ${WM_PROJECT_DIR:?}/wmake/scripts/wmakeFunctions  # Require wmake functions
+. ${WM_PROJECT_DIR:?}/wmake/scripts/have_scotch
+
+#------------------------------------------------------------------------------
+# Environment
+#   - FOAM_MPI_LIBBIN (optional: defaults to FOAM_LIBBIN/FOAM_MPI)
+
+: "${FOAM_EXT_LIBBIN:=/usr/lib$WM_COMPILER_LIB_ARCH}"  # Extra safety?
+export FOAM_EXT_LIBBIN
+
+if have_scotch
+then
+    if have_ptscotch
+    then
+        wmakeLibMpi ptscotchDecomp "scotch=$SCOTCH_VERSION"
+    fi
+fi
+
+
+#------------------------------------------------------------------------------
diff --git a/src/parallel/decompose/ptscotchDecomp/Make/files b/src/parallel/decompose/ptscotchDecomp/Make/files
index 8f83423f7e..d2494e36ba 100644
--- a/src/parallel/decompose/ptscotchDecomp/Make/files
+++ b/src/parallel/decompose/ptscotchDecomp/Make/files
@@ -1,3 +1,3 @@
 ptscotchDecomp.C
 
-LIB = $(FOAM_LIBBIN)/$(FOAM_MPI)/libptscotchDecomp
+LIB = $(FOAM_MPI_LIBBIN)/libptscotchDecomp
diff --git a/src/parallel/decompose/ptscotchDecomp/Make/options b/src/parallel/decompose/ptscotchDecomp/Make/options
index 98e715ac73..5d56198ea8 100644
--- a/src/parallel/decompose/ptscotchDecomp/Make/options
+++ b/src/parallel/decompose/ptscotchDecomp/Make/options
@@ -5,6 +5,11 @@
 sinclude $(GENERAL_RULES)/mplib$(WM_MPLIB)
 sinclude $(DEFAULT_RULES)/mplib$(WM_MPLIB)
 
+/* Default is PROJECT LIB/mpi target */
+ifeq (,$(strip $(FOAM_MPI_LIBBIN)))
+    FOAM_MPI_LIBBIN := $(FOAM_LIBBIN)/$(FOAM_MPI)
+endif
+
 EXE_INC = \
     -I$(PTSCOTCH_INC_DIR) \
     -I$(SCOTCH_INC_DIR) \
@@ -22,8 +27,8 @@ LIB_LIBS = \
     -lscotch \
     -lptscotch
 
-/* Combined into libptscotch for windows compile */
-ifneq ($(WM_OSTYPE),MSwindows)
+/* errexit, except for windows compile (already in library) */
+ifeq (,$(findstring windows,$(WM_OSTYPE)))
     LIB_LIBS += -lptscotcherrexit
 endif
 
diff --git a/src/parallel/decompose/scotchDecomp/Make/options b/src/parallel/decompose/scotchDecomp/Make/options
index 1a4bd79edd..60f174becf 100644
--- a/src/parallel/decompose/scotchDecomp/Make/options
+++ b/src/parallel/decompose/scotchDecomp/Make/options
@@ -7,8 +7,8 @@ LIB_LIBS = \
     -L$(SCOTCH_LIB_DIR) \
     -lscotch
 
-/* Combined into libscotch for windows compile */
-ifneq ($(WM_OSTYPE),MSwindows)
+/* errexit, except for windows compile (already in library) */
+ifeq (,$(findstring windows,$(WM_OSTYPE)))
     LIB_LIBS += -lscotcherrexit
 endif