diff --git a/source-builder/config/dtc-1-1.cfg b/source-builder/config/dtc-1-1.cfg
index 060c0b7..2ca99cf 100644
--- a/source-builder/config/dtc-1-1.cfg
+++ b/source-builder/config/dtc-1-1.cfg
@@ -39,7 +39,7 @@ Source0: http://www.jdl.com/software/dtc-v%{dtc_version}.tgz
 %build
   cd dtc-v%{dtc_version}
 
-  %{host_build_flags}
+  %{build_build_flags}
 
   %{__make} PREFIX=%{_prefix}
 
diff --git a/source-builder/defaults.mc b/source-builder/defaults.mc
index a2ed569..20a3f0c 100644
--- a/source-builder/defaults.mc
+++ b/source-builder/defaults.mc
@@ -263,6 +263,7 @@ else
   build_dir="build"
 fi'''
 
+# Host/build flags.
 host_build_flags:    none,    none,     '''
 # Host and build flags
 if test "%{_build}" != "%{_host}" ; then
@@ -281,6 +282,16 @@ else
 fi
 export CC CXX CC_FOR_BUILD CXX_FOR_BUILD CFLAGS CFLAGS_FOR_BUILD CXXFLAGS_FOR_BUILD'''
 
+# Build/build flags.
+build_build_flags:    none,    none,     '''
+# Build and build flags means force build == host
+# gcc is not ready to be compiled with -std=gnu99
+CC=$(echo "%{__cc} ${SB_OPT_FLAGS}" | sed -e 's,-std=gnu99 ,,')
+CXX=$(echo "%{__cxx} ${SB_OPT_FLAGS}" | sed -e 's,-std=gnu99 ,,')
+CC_FOR_BUILD=${CC}
+CXX_FOR_BUILD=${CXX}
+export CC CXX CC_FOR_BUILD CXX_FOR_BUILD CFLAGS'''
+
 # Default package settings
 _forced_static:     none,         none, '-Xlinker -Bstatic ${LIBS_STATIC} -Xlinker -Bdynamic'
 __xz:                exe,     required, '/usr/bin/xz'