diff -up radius-engine-1.1/acinclude.m4.compat-lua radius-engine-1.1/acinclude.m4
--- radius-engine-1.1/acinclude.m4.compat-lua	2013-08-10 17:45:34.638386235 -0400
+++ radius-engine-1.1/acinclude.m4	2013-08-10 17:45:46.336386411 -0400
@@ -393,7 +393,7 @@ AC_DEFUN([AM_PATH_LUA],
   LUA_CFLAGS=''
   LUA_LIBS=''
 
-  PKG_CHECK_MODULES([LUA], [lua], [HAVE_LUA=yes])
+  PKG_CHECK_MODULES([LUA], [lua-5.1], [HAVE_LUA=yes])
 
   AC_LANG_PUSH([C])
   AC_LANG_POP()