diff -r d92358eafead -r c17f3295f52c config.h.in
--- a/config.h.in	Sat Mar 05 15:51:12 2016 +0200
+++ b/config.h.in	Sat Mar 05 17:32:12 2016 +0200
@@ -22,9 +22,6 @@
 // define this to enable debugging output
 #cmakedefine DEBUG
 
-// define this, if you are building with liblua 5.2
-#cmakedefine HAVE_LUA52
-
 // define this, if your loudmouth uses SHA256 fingerprints
 #cmakedefine HAVE_LM_SHA256_FINGERPRINTS
 
@@ -40,7 +37,10 @@
 // define this, if your loudmouth have lm_ssl_set_cipher_list ()
 #cmakedefine HAVE_LM_SSL_SET_CIPHER_LIST
 
-#ifndef HAVE_LUA52
+// building against lua 5.1
+#cmakedefine LUA51_COMPATIBILITY
+
+#ifdef LUA51_COMPATIBILITY
 #  define lua_rawlen lua_objlen
 #  define luaL_setfuncs(STATE, REGTABLE, IGZERO) luaL_register ( STATE, NULL, REGTABLE )
 #endif