diff --git a/etc/tools/ThirdPartyFunctions b/etc/tools/ThirdPartyFunctions
index 60cdf36..2e27969 100644
--- a/etc/tools/ThirdPartyFunctions
+++ b/etc/tools/ThirdPartyFunctions
@@ -61,6 +61,19 @@ then
 fi
 
 
+# Test if it matches "*-none"
+_foamIsNone()
+{
+    test "${1##*-}" = none
+}
+
+# Test if it matches "*-system"
+_foamIsSystem()
+{
+    test "${1##*-}" = system
+}
+
+
 #
 # Download file $1 from url $2 into download/ directory
 #
diff --git a/makeCGAL b/makeCGAL
index 8d2f9e8..32aa5f8 100755
--- a/makeCGAL
+++ b/makeCGAL
@@ -59,15 +59,17 @@ wmakeCheckPwd "$WM_THIRD_PARTY_DIR" || {
 }
 . etc/tools/ThirdPartyFunctions
 #------------------------------------------------------------------------------
+Script="${0##*/}"
 
 usage() {
     exec 1>&2
     while [ "$#" -ge 1 ]; do echo "$1"; shift; done
     cat<<USAGE
 
-usage: ${0##*/} [OPTION] [CGAL-VERSION] [boost-VERSION] [gmp-VERSION] [mpfr-VERSION]
+usage: $Script [OPTION] [CGAL-VERSION] [boost-VERSION] [gmp-VERSION] [mpfr-VERSION]
 options:
   -gcc              force g++ instead of the value from \$WM_CXX
+  -system           use system versions for boost/gmp/mpfr
   -help
 
 * build CGAL with
@@ -77,9 +79,9 @@ options:
       $mpfrPACKAGE
 
 Normally builds against ThirdParty boost and gmp/mpfr when possible.
-To override this behaviour (and use the system boost and/o gmp/mpfr),
+To override this behaviour (and use the system boost and/or gmp/mpfr),
 simply specify a 'system' version. For example,
-    ${0##*/} boost-system gmp-system
+    $Script boost-system gmp-system
 
 Note: mixing system and ThirdParty for gmp/mpfr is not supported.
 
@@ -106,11 +108,17 @@ do
         export CXX=g++   # use g++
         shift
         ;;
-    gmp-[4-9]* | gmp-sys*)
+    -sys*)
+        gmpPACKAGE="gmp-system"
+        mpfrPACKAGE="mpfr-system"
+        boostPACKAGE="boost-system"
+        shift
+        ;;
+    gmp-[4-9]* | gmp-system)
         gmpPACKAGE="${1%%/}"
         shift
         ;;
-    mpfr-[2-9]* | mpfr-sys*)
+    mpfr-[2-9]* | mpfr-system)
         mpfrPACKAGE="${1%%/}"
         shift
         ;;
@@ -118,7 +126,7 @@ do
         cgalPACKAGE="${1%%/}"
         shift
         ;;
-    boost-[0-9]* | boost_[0-9]* | boost-sys* )
+    boost-[0-9]* | boost_[0-9]* | boost-system )
         boostPACKAGE="${1%%/}"
         shift
         ;;
@@ -146,12 +154,27 @@ if [ -d "$BOOST_ARCH_PATH" ]
 then
     boostInc="$BOOST_ARCH_PATH/include"
     boostLib="$BOOST_ARCH_PATH/lib"
-elif [ -d "$BOOST_SOURCE_DIR" ]
+elif _foamIsSystem $BOOST_ARCH_PATH
 then
+    echo "Using boost-system"
+
+    boostInc="/usr/include"
+
+    # For completeness:
+    # 64-bit needs lib64, but 32-bit needs lib (not lib32)
+    if [ "$WM_ARCH_OPTION" = 64 ]
+    then
+        boostLib="/usr/lib$WM_ARCH_OPTION"
+    else
+        boostLib="/usr/lib"
+    fi
+else
+    echo "Starting build: boost"
+    echo
+
     boostInc="$BOOST_ARCH_PATH/include"
     boostLib="$BOOST_ARCH_PATH/lib"
 
-    echo "Starting build: boost"
     (
         cd $BOOST_SOURCE_DIR || exit 1
 
@@ -167,17 +190,13 @@ then
         echo "Error building: boost"
         exit 1
     }
-else
-    boostInc="/usr/include"
+fi
 
-    # For completeness:
-    # 64-bit needs lib64, but 32-bit needs lib (not lib32)
-    if [ "$WM_ARCH_OPTION" = 64 ]
-    then
-        boostLib="/usr/lib$WM_ARCH_OPTION"
-    else
-        boostLib="/usr/lib"
-    fi
+# nothing to build
+if _foamIsSystem "$cgalPACKAGE"
+then
+    echo "Using CGAL-system"
+    exit 0
 fi
 
 # nothing left to build
@@ -242,7 +261,7 @@ MPFR_ARCH_PATH=$installBASE/$mpfrPACKAGE
 
     cd $CGAL_BINARY_DIR || exit 1
 
-    unset configBoost configGmpMpfr
+    unset configBoost configGmp configMpfr
     echo "----"
     echo "Configuring $cgalPACKAGE with boost $BOOST_VERSION_NO"
     echo "    Source         : $CGAL_SOURCE_DIR"
@@ -271,22 +290,32 @@ CMAKE_OPTIONS
 )
     fi
 
-    if [ -d "$GMP_ARCH_PATH" -a -d "$MPFR_ARCH_PATH" ]
+    if [ -d "$GMP_ARCH_PATH" ]
     then
-        echo "    ThirdParty     : gmp/mpfr"
-        configGmpMpfr=$(cat <<CMAKE_OPTIONS
+        echo "    ThirdParty     : gmp"
+        configGmp=$(cat <<CMAKE_OPTIONS
  -DGMP_INCLUDE_DIR=$GMP_ARCH_PATH/include
  -DGMP_LIBRARIES_DIR=$GMP_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH
  -DGMP_LIBRARIES=$GMP_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH/libgmp.so
  -DGMPXX_INCLUDE_DIR=$GMP_ARCH_PATH/include
  -DGMPXX_LIBRARIES=$GMP_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH/libgmpxx.so
+CMAKE_OPTIONS
+)
+    else
+        echo "    system         : gmp"
+    fi
+
+    if [ -d "$MPFR_ARCH_PATH" ]
+    then
+        echo "    ThirdParty     : mpfr"
+        configMpfr=$(cat <<CMAKE_OPTIONS
  -DMPFR_INCLUDE_DIR=$MPFR_ARCH_PATH/include
  -DMPFR_LIBRARIES_DIR=$MPFR_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH
  -DMPFR_LIBRARIES=$MPFR_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH/libmpfr.so
 CMAKE_OPTIONS
 )
     else
-        echo "    system         : gmp/mpfr"
+        echo "    system         : mpfr"
     fi
 
     echo "----"
@@ -295,7 +324,7 @@ CMAKE_OPTIONS
         -DCMAKE_INSTALL_PREFIX=$CGAL_ARCH_PATH \
         -DCMAKE_BUILD_TYPE=Release \
         -DWITH_CGAL_Qt5=OFF \
-        $configBoost $configGmpMpfr \
+        $configBoost $configGmp $configMpfr \
         $CGAL_SOURCE_DIR \
     && make -j $WM_NCOMPPROCS \
     && make install || exit 1
diff --git a/makeGcc b/makeGcc
index b337cb9..70721c4 100755
--- a/makeGcc
+++ b/makeGcc
@@ -28,6 +28,10 @@
 # Description
 #     Build script gcc and gmp, mpfr, mpc.
 #
+#     Normally builds against ThirdParty gmp/mpfr when possible.
+#     To override this behaviour (and use the system gmp/mpfr/mpc),
+#     simply specify a 'system' version. For example,
+#         makeGcc gmp-system
 #
 #------------------------------------------------------------------------------
 # get default GCC, mpfr, gmp and mpc versions
@@ -62,6 +66,7 @@ usage() {
 usage: $Script [OPTION] [gcc-VERSION] [gmp-VERSION] [mpfr-VERSION] [mpc-VERSION]
 options:
   -no-multilib      for 64-bit systems without 32-bit support
+  -system           use system versions for gmp/mpfr/mpc
   -help
 
 * build combinations of gmp, mpfr, mpc and gcc
@@ -88,15 +93,21 @@ do
         GCC_BUILD_OPTIONS="--disable-multilib"
         shift
         ;;
-    gmp-[4-9]*)
+    -sys*)
+        gmpPACKAGE="gmp-system"
+        mpfrPACKAGE="mpfr-system"
+        mpcPACKAGE="mpc-system"
+        shift
+        ;;
+    gmp-[4-9]* | gmp-system)
         gmpPACKAGE="${1%%/}"
         shift
         ;;
-    mpfr-[2-9]*)
+    mpfr-[2-9]* | mpfr-system)
         mpfrPACKAGE="${1%%/}"
         shift
         ;;
-    mpc-[0-9]*)
+    mpc-[0-9]* | mpc-system)
         mpcPACKAGE="${1%%/}"
         shift
         ;;
@@ -116,6 +127,15 @@ then
     exit 1
 fi
 
+cat<<SUMMARY
+GCC configuration
+------------------
+    GCC     = $gccPACKAGE
+    GMP     = $gmpPACKAGE
+    MPFR    = $mpfrPACKAGE
+    MPC     = $mpcPACKAGE
+------------------
+SUMMARY
 
 # Set 32 or 64 bit ABI
 case "$WM_ARCH_OPTION" in
@@ -138,6 +158,7 @@ GMP_ARCH_PATH=$installBASE/$gmpPACKAGE
 MPFR_ARCH_PATH=$installBASE/$mpfrPACKAGE
 MPC_ARCH_PATH=$installBASE/$mpcPACKAGE
 
+
 # ================
 # Build GMP
 # ================
@@ -145,6 +166,9 @@ echo "---------------"
 if [ -d $GMP_ARCH_PATH ]
 then
     echo "Already built: $gmpPACKAGE"
+elif _foamIsSystem $GMP_ARCH_PATH
+then
+    echo "Using gmp-system"
 else
     echo "Starting build: $gmpPACKAGE"
     echo
@@ -186,6 +210,9 @@ echo "---------------"
 if [ -d $MPFR_ARCH_PATH ]
 then
     echo "Already built: $mpfrPACKAGE"
+elif _foamIsSystem $MPFR_ARCH_PATH
+then
+    echo "Using mpfr-system"
 else
     echo "Starting build: $mpfrPACKAGE"
     echo
@@ -228,6 +255,9 @@ echo "---------------"
 if [ -d $MPC_ARCH_PATH ]
 then
     echo "Already built: $mpcPACKAGE"
+elif _foamIsSystem $MPC_ARCH_PATH
+then
+    echo "Using mpc-system"
 else
     echo "Starting build: $mpcPACKAGE"
     echo
@@ -290,6 +320,10 @@ else
     mkdir -p $buildDIR
     cd $buildDIR
 
+    _foamIsSystem "$GMP_ARCH_PATH"  && GMP_ARCH_PATH=/usr  # revert to system
+    _foamIsSystem "$MPFR_ARCH_PATH" && MPFR_ARCH_PATH=/usr # revert to system
+    _foamIsSystem "$MPC_ARCH_PATH"  && MPC_ARCH_PATH=/usr  # revert to system
+
     set -x
     $sourceDIR/configure \
         --prefix=$GCC_ARCH_PATH \