diff --git a/google/genai/types.py b/google/genai/types.py
index d421a36bf..4f938d4b4 100644
--- a/google/genai/types.py
+++ b/google/genai/types.py
@@ -5405,10 +5405,10 @@ class GenerateContentConfigDict(TypedDict, total=False):
 ]
 
 
-ContentListUnion = Union[ContentUnion, list[ContentUnion]]
+ContentListUnion = Union[ContentUnion, Sequence[ContentUnion]]
 
 
-ContentListUnionDict = Union[ContentUnionDict, list[ContentUnionDict]]
+ContentListUnionDict = Union[ContentUnionDict, Sequence[ContentUnionDict]]
 
 
 class _GenerateContentParameters(_common.BaseModel):