--- ext/augeas/extconf.rb.~1~	2012-10-26 10:39:01.240720232 +0200
+++ ext/augeas/extconf.rb	2012-10-26 10:53:12.413324140 +0200
@@ -27,4 +27,8 @@
     raise "augeas-devel not installed"
 end
 
+unless pkg_config("libxml-2.0")
+    raise "libxml2-devel not installed"
+end
+
 create_makefile(extension_name)