diff --git a/backend/open_webui/routers/ollama.py b/backend/open_webui/routers/ollama.py
index fcb263d1e..775cd0446 100644
--- a/backend/open_webui/routers/ollama.py
+++ b/backend/open_webui/routers/ollama.py
@@ -1197,7 +1197,7 @@ class OpenAIChatMessageContent(BaseModel):
 
 class OpenAIChatMessage(BaseModel):
     role: str
-    content: Union[str, list[OpenAIChatMessageContent]]
+    content: Union[Optional[str], list[OpenAIChatMessageContent]]
 
     model_config = ConfigDict(extra="allow")