diff --git a/ext/semian/extconf.rb b/ext/semian/extconf.rb
index 93b05a283..d61560d5e 100644
--- a/ext/semian/extconf.rb
+++ b/ext/semian/extconf.rb
@@ -23,7 +23,7 @@
 have_func 'rb_thread_blocking_region'
 have_func 'rb_thread_call_without_gvl'
 
-$CFLAGS = "-D_GNU_SOURCE -Werror -Wall "
+$CFLAGS = "-D_GNU_SOURCE -Wall "
 if ENV.has_key?('DEBUG')
   $CFLAGS << "-O0 -g"
 else