diff --git a/lua/gp/config.lua b/lua/gp/config.lua
index d4ddcd8d..23a45651 100644
--- a/lua/gp/config.lua
+++ b/lua/gp/config.lua
@@ -122,7 +122,7 @@ local config = {
 			chat = true,
 			command = false,
 			-- string with model name or table with model name and parameters
-			model = { model = "gpt-4", temperature = 1.1, top_p = 1 },
+			model = { model = "gpt-4o", temperature = 1.1, top_p = 1 },
 			-- system prompt (use this to specify the persona/role of the AI)
 			system_prompt = require("gp.defaults").chat_system_prompt,
 		},
@@ -220,7 +220,7 @@ local config = {
 			chat = false,
 			command = true,
 			-- string with the Copilot engine name or table with engine name and parameters if applicable
-			model = { model = "gpt-4", temperature = 0.8, top_p = 1, n = 1 },
+			model = { model = "gpt-4o", temperature = 0.8, top_p = 1, n = 1 },
 			-- system prompt (use this to specify the persona/role of the AI)
 			system_prompt = require("gp.defaults").code_system_prompt,
 		},
diff --git a/lua/gp/dispatcher.lua b/lua/gp/dispatcher.lua
index 932b9fe3..e3e41e5a 100644
--- a/lua/gp/dispatcher.lua
+++ b/lua/gp/dispatcher.lua
@@ -44,13 +44,9 @@ D.setup = function(opts)
 		end
 	end
 
-
+	local callbacks = { copilot = vault.refresh_copilot_bearer }
 	for name, provider in pairs(D.providers) do
-		if name == "copilot" then
-			vault.resolve_secret(name, provider.secret, vault.refresh_copilot_bearer)
-		else
-			vault.resolve_secret(name, provider.secret)
-		end
+		vault.resolve_secret(name, provider.secret, callbacks[name])
 		provider.secret = nil
 	end
 
@@ -152,6 +148,10 @@ D.prepare_payload = function(messages, model, provider)
 		return payload
 	end
 
+	if provider == "copilot" and model.model == "gpt-4o" then
+		model.model = "gpt-4o-2024-05-13"
+	end
+
 	return {
 		model = model.model,
 		stream = true,
@@ -304,7 +304,9 @@ D.query = function(buf, provider, payload, handler, on_exit, callback)
 	if provider == "copilot" then
 		vault.refresh_copilot_bearer()
 		bearer = vault.get_secret("copilot_bearer")
-		if not bearer then
+		local expires_at = vault.get_secret("copilot_bearer_expires_at")
+		if not bearer or not expires_at or expires_at < os.time() then
+			logger.warning("copilot bearer token is missing or expired, trying to refresh..")
 			return
 		end
 		headers = {
diff --git a/lua/gp/vault.lua b/lua/gp/vault.lua
index 78d599a2..141bf7a5 100644
--- a/lua/gp/vault.lua
+++ b/lua/gp/vault.lua
@@ -136,6 +136,7 @@ V.refresh_copilot_bearer = function()
 	if bearer.token and bearer.expires_at and bearer.expires_at > os.time() then
 		logger.debug("vault refresh_copilot_bearer token still valid", true)
 		secrets.copilot_bearer = bearer.token
+		secrets.copilot_bearer_expires_at = bearer.expires_at
 		return
 	end