diff --git a/source-builder/config/gcc-4.8-1.cfg b/source-builder/config/gcc-4.8-1.cfg
index f81cbf7..02689db 100644
--- a/source-builder/config/gcc-4.8-1.cfg
+++ b/source-builder/config/gcc-4.8-1.cfg
@@ -143,10 +143,13 @@ BuildRoot: %{_tmppath}/%{name}-root-%(%{__id_u} -n)
 %endif
 %if "%{_build}" != "%{_host}"
   CFLAGS_FOR_BUILD="-g -O2 -Wall" \
+  CXXFLAGS_FOR_BUILD="-g -O2 -Wall" \
   CC="%{_host}-gcc ${SB_OPT_FLAGS}" \
+  CXX="%{_host}-g++ ${SB_OPT_FLAGS}" \
 %else
   # gcc is not ready to be compiled with -std=gnu99
   CC=$(echo "%{__cc} ${SB_OPT_FLAGS}" | sed -e 's,-std=gnu99 ,,') \
+  CXX=$(echo "%{__cxx} ${SB_OPT_FLAGS}" | sed -e 's,-std=gnu99 ,,') \
 %endif
   ../gcc-%{gcc_version}/configure \
     --prefix=%{_prefix} \
diff --git a/source-builder/sb/defaults.py b/source-builder/sb/defaults.py
index c2c9457..8beee60 100644
--- a/source-builder/sb/defaults.py
+++ b/source-builder/sb/defaults.py
@@ -176,6 +176,7 @@ export SB_BUILD_ROOT
 %{?_targetcflags:CFLAGS_FOR_TARGET="%{_targetcflags}"}
 %{?_targetcxxflags:CXXFLAGS_FOR_TARGET="%{_targetcxxflags}"}
 export CFLAGS_FOR_TARGET
+export CXXFLAGS_FOR_TARGET
 # Default environment set up.
 LANG=C
 export LANG