diff --git a/pyproject.toml b/pyproject.toml
index efbb5db..fb62fa4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,7 +20,7 @@ dependencies = [
     "requests",
     "python-dotenv",
     "azure-ai-evaluation==1.8.0",
-    "marshmallow==3.23.2", # Older version required due to promptflow issue with _T import
+    "marshmallow==4.1.0", # Older version required due to promptflow issue with _T import
     "azure-search-documents",
     "typer",
     "openai>=1.56.1", # Includes fix for httpx proxies issues