diff --git a/ext/nokogiri/extconf.rb b/ext/nokogiri/extconf.rb
index 4278dd6e46..fb36a0ff6e 100644
--- a/ext/nokogiri/extconf.rb
+++ b/ext/nokogiri/extconf.rb
@@ -594,6 +594,9 @@ def do_clean
 append_ldflags(ENV["LDFLAGS"].split) unless ENV["LDFLAGS"].nil?
 $LIBS = concat_flags($LIBS, ENV["LIBS"])
 
+# c99 is old enough to drink
+append_cflags(["-std=c99", "-Wno-declaration-after-statement"])
+
 # always include debugging information
 append_cflags("-g")