diff -Naurp dovecot-2.3.15.orig/src/lib-lua/dlua-dovecot.c dovecot-2.3.15/src/lib-lua/dlua-dovecot.c
--- dovecot-2.3.15.orig/src/lib-lua/dlua-dovecot.c	2021-06-14 08:40:37.000000000 -0500
+++ dovecot-2.3.15/src/lib-lua/dlua-dovecot.c	2021-06-25 11:56:57.792455236 -0500
@@ -268,7 +268,7 @@ void dlua_push_event(lua_State *L, struc
 	luaL_setmetatable(L, DLUA_EVENT);
 
 	/* we need to attach gc to userdata to support older lua*/
-	struct event **ptr = lua_newuserdata(L, sizeof(struct event*));
+	struct event **ptr = lua_newuserdatauv(L, sizeof(struct event*), 0);
 	*ptr = event;
 	lua_createtable(L, 0, 1);
 	lua_pushcfunction(L, dlua_event_gc);
diff -Naurp dovecot-2.3.15.orig/src/lib-lua/dlua-resume.c dovecot-2.3.15/src/lib-lua/dlua-resume.c
--- dovecot-2.3.15.orig/src/lib-lua/dlua-resume.c	2021-06-14 08:40:37.000000000 -0500
+++ dovecot-2.3.15/src/lib-lua/dlua-resume.c	2021-06-25 11:52:23.313925270 -0500
@@ -117,7 +117,7 @@ static void dlua_pcall_yieldable_continu
 	dlua_tls_clear(L, RESUME_TIMEOUT);
 	dlua_tls_clear(L, RESUME_NARGS);
 
-	ret = lua_resume(L, L, nargs);
+	ret = lua_resume(L, L, nargs, NULL);
 	if (ret == LUA_YIELD) {
 		/*
 		 * thread yielded - nothing to do
@@ -180,7 +180,7 @@ int dlua_pcall_yieldable(lua_State *L, c
 	lua_insert(L, -(nargs + 1));
 
 	/* stack: func, args (top) */
-	ret = lua_resume(L, L, nargs);
+	ret = lua_resume(L, L, nargs, NULL);
 	if (ret == LUA_YIELD) {
 		/*
 		 * thread yielded - nothing to do