diff --git a/pkgs/development/compilers/gcc/4.7/builder.sh b/pkgs/development/compilers/gcc/4.7/builder.sh
index 1771121bc7c..638e3b71a93 100644
--- a/pkgs/development/compilers/gcc/4.7/builder.sh
+++ b/pkgs/development/compilers/gcc/4.7/builder.sh
@@ -97,7 +97,7 @@ if test "$noSysDirs" = "1"; then
             # The path to the Glibc binaries such as `crti.o'.
             glibc_dir="$(cat $NIX_GCC_CROSS/nix-support/orig-libc)"
             glibc_libdir="$glibc_dir/nix-support/orig-libc)/lib"
-            configureFlags="--with-native-system-header-dir=$glibc_dir/include"
+            configureFlags="$configureFlags --with-native-system-header-dir=$glibc_dir/include"
 
             extraFlags="-I$NIX_FIXINC_DUMMY_CROSS $extraFlags"
             extraLDFlags="-L$glibc_libdir -rpath $glibc_libdir $extraLDFlags"