diff --git a/makeGcc b/makeGcc
index 742d564..a4223e2 100755
--- a/makeGcc
+++ b/makeGcc
@@ -4,7 +4,7 @@
 # \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
 #  \\    /   O peration     |
 #   \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
-#    \\/     M anipulation  |
+#    \\/     M anipulation  | Copyright (C) 2016 OpenCFD Ltd.
 #------------------------------------------------------------------------------
 # License
 #     This file is part of OpenFOAM.
@@ -74,6 +74,7 @@ usage: $Script [OPTION] [gcc-VERSION] [gmp-VERSION] [mpfr-VERSION] [mpc-VERSION]
 options:
   -multilib         for 64-bit systems with 32-bit support required
   -no-multilib      for 64-bit systems without 32-bit support (DEFAULT)
+  -no-threadsafe    disable mpfr thread-safe (default is auto-detect)
   -system           use system versions for gmp/mpfr/mpc
   -help
 
@@ -90,6 +91,7 @@ USAGE
 
 # build 32-bit libraries on 64-bit systems (normally not needed)
 optMultilib=disable
+unset optThreadSafe # unset=auto
 
 # Parse options
 while [ "$#" -gt 0 ]
@@ -104,6 +106,9 @@ do
     -no-multi*)
         optMultilib=disable
         ;;
+    -no-thread*)
+        optThreadSafe=disable
+        ;;
     -sys*)
         gmpPACKAGE="gmp-system"
         mpfrPACKAGE="mpfr-system"
@@ -118,7 +123,7 @@ do
     mpc-[0-9]* | mpc-system)
         mpcPACKAGE="${1%%/}"
         ;;
-    gcc-[4-9]*)
+    gcc-[4-9]* | gcc-system)
         gccPACKAGE="${1%%/}"
         ;;
     *)
@@ -203,6 +208,14 @@ fi
 if [ -d "$GMP_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH" ]
 then
     _foamAddLib "$GMP_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH"
+
+    configGMP=$(cat <<CONFIG_OPTIONS
+    --with-gmp-include=$GMP_ARCH_PATH/include
+    --with-gmp-lib=$GMP_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH
+CONFIG_OPTIONS
+)
+else
+    unset configGMP
 fi
 
 
@@ -230,12 +243,15 @@ else
     mkdir -p $buildDIR
     cd $buildDIR
 
+    unset configOpt
+    # explicitly enable/disable thread-safe
+    [ -n "$optThreadSafe" ] && configOpt="--${optThreadSafe}-thread-safe"
+
     set -x
     $sourceDIR/configure ABI=$ABI \
-       --prefix=$MPFR_ARCH_PATH \
-       --libdir=$MPFR_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH \
-       --with-gmp-include=$GMP_ARCH_PATH/include \
-       --with-gmp-lib=$GMP_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH \
+        --prefix=$MPFR_ARCH_PATH \
+        --libdir=$MPFR_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH \
+        $configGMP $configOpt \
     && make -j $WM_NCOMPPROCS \
     && make install \
     && echo "Built: $mpfrPACKAGE"
@@ -248,6 +264,14 @@ fi
 if [ -d "$MPFR_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH" ]
 then
     _foamAddLib "$MPFR_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH"
+
+    configMPFR=$(cat <<CONFIG_OPTIONS
+    --with-mpfr-include=$MPFR_ARCH_PATH/include \
+    --with-mpfr-lib=$MPFR_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH
+CONFIG_OPTIONS
+)
+else
+    unset configMPFR
 fi
 
 
@@ -279,10 +303,7 @@ else
     $sourceDIR/configure ABI=$ABI \
         --prefix=$MPC_ARCH_PATH \
         --libdir=$MPC_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH \
-        --with-gmp-include=$GMP_ARCH_PATH/include \
-        --with-gmp-lib=$GMP_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH \
-        --with-mpfr-include=$MPFR_ARCH_PATH/include \
-        --with-mpfr-lib=$MPFR_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH \
+        $configGMP $configMPFR \
     && make -j $WM_NCOMPPROCS \
     && make install \
     && echo "Built: $mpcPACKAGE"
@@ -295,6 +316,14 @@ fi
 if [ -d "$MPC_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH" ]
 then
     _foamAddLib "$MPC_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH"
+
+    configMPC=$(cat <<CONFIG_OPTIONS
+    --with-mpc-include=$MPC_ARCH_PATH/include \
+    --with-mpc-lib=$MPC_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH
+CONFIG_OPTIONS
+)
+else
+    unset configMPC
 fi
 
 
@@ -309,6 +338,9 @@ echo "---------------"
 if [ -d $GCC_ARCH_PATH ]
 then
     echo "Already built: $gccPACKAGE"
+elif _foamIsSystem $GCC_ARCH_PATH
+then
+    echo "Using gcc-system"
 else
     echo "Starting build: $gccPACKAGE"
     echo
@@ -323,10 +355,6 @@ 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 "$MPC_ARCH_PATH"  && MPC_ARCH_PATH=/usr  # revert to system
-
     unset configOpt
     # with/without multi-lib (32-bit support on 64-bit systems)
     [ -n "$optMultilib" ] && configOpt="--${optMultilib}-multilib"
@@ -334,18 +362,12 @@ else
     set -x
     $sourceDIR/configure \
         --prefix=$GCC_ARCH_PATH \
-        --with-gmp-include=$GMP_ARCH_PATH/include \
-        --with-gmp-lib=$GMP_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH \
-        --with-mpfr-include=$MPFR_ARCH_PATH/include \
-        --with-mpfr-lib=$MPFR_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH \
-        --with-mpc-include=$MPC_ARCH_PATH/include \
-        --with-mpc-lib=$MPC_ARCH_PATH/lib$WM_COMPILER_LIB_ARCH \
         --with-pkgversion=OpenFOAM \
         --enable-languages=c,c++ \
         --enable-__cxa_atexit \
         --enable-libstdcxx-allocator=new \
         --with-system-zlib \
-        $configOpt \
+        $configGMP $configMPFR $configMPC $configOpt \
         MAKEINFO=missing \
     && make -j $WM_NCOMPPROCS \
     && make install \