diff --git a/vmf/scripts/mods/vmf/modules/core/misc.lua b/vmf/scripts/mods/vmf/modules/core/misc.lua
index a6107c7..2c099f5 100644
--- a/vmf/scripts/mods/vmf/modules/core/misc.lua
+++ b/vmf/scripts/mods/vmf/modules/core/misc.lua
@@ -19,6 +19,15 @@ function vmf.check_wrong_argument_type(mod, vmf_function_name, argument_name, ar
   return true
 end
 
+function vmf.check_old_vmf()
+  local old_vmf_table = rawget(_G, "Mods")
+
+  if old_vmf_table and old_vmf_table.exec then
+    error("Unfortunately, workshop mods and old-fashioned mods (VMF-pack or QoL) are incompatible. " ..
+           "Either remove old mods or disable workshop mods.")
+  end
+end
+
 function vmf.throw_error(error_message, ...)
   error(string.format(error_message, ...), 0)
 end
\ No newline at end of file
diff --git a/vmf/scripts/mods/vmf/vmf_loader.lua b/vmf/scripts/mods/vmf/vmf_loader.lua
index aaf1a82..b600a94 100644
--- a/vmf/scripts/mods/vmf/vmf_loader.lua
+++ b/vmf/scripts/mods/vmf/vmf_loader.lua
@@ -99,6 +99,7 @@ end
 
 function vmf_mod_object:on_game_state_changed(status, state)
 	print("VMF:ON_GAME_STATE_CHANGED(), status: " .. tostring(status) .. ", state: " .. tostring(state))
+	if VT1 then vmf.check_old_vmf() end
 	vmf.mods_game_state_changed_event(status, state)
 	vmf.save_unsaved_settings_to_file()
 	vmf.apply_delayed_hooks(status, state)