diff --git a/lmm_tools/lmm/lmm.py b/lmm_tools/lmm/lmm.py
index e4c80032..c9c38945 100644
--- a/lmm_tools/lmm/lmm.py
+++ b/lmm_tools/lmm/lmm.py
@@ -4,7 +4,7 @@
 from typing import Optional, Union
 
 
-def encode_image(image: str | Path) -> str:
+def encode_image(image: Union[str, Path]) -> str:
     with open(image, "rb") as f:
         encoded_image = base64.b64encode(f.read()).decode("utf-8")
     return encoded_image