当我尝试安装Ruby gem sequel_pg时，我得到以下错误meassage：
~$ sudo gem update
Updating installed gems
Updating sequel_pg
Building native extensions. This could take a while...
ERROR: Error installing sequel_pg:
ERROR: Failed to build gem native extension.
/usr/bin/ruby1.9.1 extconf.rb
checking for main() in -lpq... yes
checking for libpq-fe.h... yes
checking for PQsetSingleRowMode()... no
creating Makefile
make
compiling sequel_pg.c
sequel_pg.c: In function ‘spg_timestamp_error’:
sequel_pg.c:279:3: error: format not a string literal and no format arguments [- Werror=format-security]
cc1: some warnings being treated as errors
make: *** [sequel_pg.o] Error 1
Gem files will remain installed in /var/lib/gems/1.9.1/gems/sequel_pg-1.6.5 for inspection.
Results logged to /var/lib/gems/1.9.1/gems/sequel_pg-1.6.5/ext/sequel_pg/gem_make.out
Nothing to update
我正在运行Lubuntu 13.04。依赖：pg和续集已安装。还安装了包文件postgresql和postgresql-server-dev-9.1
有没有人有线索？