diff --git a/chat_stream.go b/chat_stream.go
index b5257ccc4..9ed0bc70a 100644
--- a/chat_stream.go
+++ b/chat_stream.go
@@ -7,7 +7,8 @@ import (
 )
 
 type ChatCompletionStreamChoiceDelta struct {
-	Content string `json:"content"`
+	Content string `json:"content,omitempty"`
+	Role    string `json:"role,omitempty"`
 }
 
 type ChatCompletionStreamChoice struct {