--- a/util/prosodyctl.lua	Fri Mar 26 13:03:22 2021 +0100
+++ b/util/prosodyctl.lua	Tue Mar 16 02:44:22 2021 +0100
@@ -221,8 +221,8 @@
 
 local function call_luarocks(operation, mod, server)
 	local dir = prosody.paths.installer;
-	local ok, _, code = os.execute(render_cli("luarocks {op} --tree={dir} {server&--server={server}} {mod?}", {
-				dir = dir; op = operation; mod = mod; server = server;
+	local ok, _, code = os.execute(render_cli("luarocks --lua-version={luav} {op} --tree={dir} {server&--server={server}} {mod?}", {
+				dir = dir; op = operation; mod = mod; server = server; luav = _VERSION:match("5%.%d");
 		}));
 	if type(ok) == "number" then code = ok; end
 	return code;