diff --git a/Allwmake b/Allwmake
--- a/Allwmake
+++ b/Allwmake
@@ -52,6 +52,13 @@
 [ -n "$WM_CXXFLAGS" ]   &&  export CXXFLAGS="$WM_CXXFLAGS"
 [ -n "$WM_LDFLAGS" ]    &&  export LDFLAGS="$WM_LDFLAGS"
 
+if [ "$WM_ARCH_BASE" == "darwin" ]
+then
+    export WM_SO_EXTENSION=dylib
+else
+    export WM_SO_EXTENSION=so
+fi
+
 echo
 echo ========================================
 echo Start ThirdParty Allwmake
@@ -187,10 +194,14 @@
 
 # this needs generalizing
 scotchMakefile=../../etc/wmakeFiles/scotch/Makefile.inc.i686_pc_linux2.shlib-OpenFOAM-$WM_ARCH_OPTION
+if [ "$WM_ARCH_BASE" == "darwin" ]
+then
+    scotchMakefile=../../etc/wmakeFiles/scotch/Makefile.inc.i686_mac_darwin.shlib-OpenFOAM
+fi
 
 if [ -f $SCOTCH_ARCH_PATH/include/scotch.h \
-  -a -r $FOAM_EXT_LIBBIN/libscotch.so \
-  -a -r $FOAM_EXT_LIBBIN/libscotcherrexit.so ]
+  -a -r $FOAM_EXT_LIBBIN/libscotch.$WM_SO_EXTENSION \
+  -a -r $FOAM_EXT_LIBBIN/libscotcherrexit.$WM_SO_EXTENSION ]
 then
     echo "    scotch header in $SCOTCH_ARCH_PATH/include"
     echo "    scotch libs   in $FOAM_EXT_LIBBIN"
@@ -250,8 +261,8 @@
     echo
 
     if [ -f $SCOTCH_ARCH_PATH/include/$FOAM_MPI/ptscotch.h \
-      -a -r $FOAM_EXT_LIBBIN/$FOAM_MPI/libptscotch.so \
-      -a -r $FOAM_EXT_LIBBIN/$FOAM_MPI/libptscotcherrexit.so ]
+      -a -r $FOAM_EXT_LIBBIN/$FOAM_MPI/libptscotch.$WM_SO_EXTENSION \
+      -a -r $FOAM_EXT_LIBBIN/$FOAM_MPI/libptscotcherrexit.$WM_SO_EXTENSION ]
     then
         echo "    ptscotch header in $SCOTCH_ARCH_PATH/include/$FOAM_MPI"
         echo "    ptscotch libs   in $FOAM_EXT_LIBBIN/$FOAM_MPI"
@@ -330,3 +341,4 @@
 
 
 # ----------------------------------------------------------------- end-of-file
+# vim:et:sw=4:ts=4
diff --git a/etc/wmakeFiles/scotch/Makefile.inc.i686_mac_darwin.shlib-OpenFOAM b/etc/wmakeFiles/scotch/Makefile.inc.i686_mac_darwin.shlib-OpenFOAM
new file mode 100644
--- /dev/null
+++ b/etc/wmakeFiles/scotch/Makefile.inc.i686_mac_darwin.shlib-OpenFOAM
@@ -0,0 +1,21 @@
+EXE		=
+LIB		= .dylib
+OBJ		= .o
+
+MAKE		= make
+AR		= $(WM_CC)
+ARFLAGS		= -dynamiclib -undefined dynamic_lookup -o
+CAT		= cat
+CCS		= clang
+CCP		= mpicc
+CCD		= mpicc
+CFLAGS		= -O3 -DCOMMON_FILE_COMPRESS_GZ -DCOMMON_RANDOM_FIXED_SEED -DSCOTCH_RENAME -DSCOTCH_RENAME_PARSER -Drestrict=__restrict -DCOMMON_TIMING_OLD
+CLIBFLAGS	= -fPIC
+LDFLAGS		= -lz -lm
+CP		= cp
+LEX		= flex -Pscotchyy -olex.yy.c
+LN		= ln
+MKDIR		= mkdir
+MV		= mv
+RANLIB		= echo
+YACC		= bison -pscotchyy -y -b y