diff --git a/src/luacheck/builtin_standards.lua b/src/luacheck/builtin_standards.lua
index aae0f65c..199d4ea2 100644
--- a/src/luacheck/builtin_standards.lua
+++ b/src/luacheck/builtin_standards.lua
@@ -257,7 +257,8 @@ lua_defs.luajit = add_defs(make_min_def("luajit"), {
 lua_defs.ngx_lua = add_defs(lua_defs.luajit, {
    fields = {
       ngx = {other_fields = true, read_only = false},
-      ndk = {other_fields = true}
+      ndk = {other_fields = true},
+      coroutine = {other_fields = true}
    }
 })
 lua_defs.max = add_defs(lua_defs.lua51c, lua_defs.lua52c, lua_defs.lua53c, lua_defs.luajit)