diff --git a/internal/agent/coordinator.go b/internal/agent/coordinator.go
index ffcccf94d1448094f0c76fac5bcd7307b74b97fe..7bf0167fa1cf0de0323e3227823bbc9c4ab99e5c 100644
--- a/internal/agent/coordinator.go
+++ b/internal/agent/coordinator.go
@@ -654,6 +654,9 @@ func (c *coordinator) isAnthropicThinking(model config.SelectedModel) bool {
 
 func (c *coordinator) buildProvider(providerCfg config.ProviderConfig, model config.SelectedModel) (fantasy.Provider, error) {
 	headers := maps.Clone(providerCfg.ExtraHeaders)
+	if headers == nil {
+		headers = make(map[string]string)
+	}
 
 	// handle special headers for anthropic
 	if providerCfg.Type == anthropic.Name && c.isAnthropicThinking(model) {