diff --git a/backend/requirements.txt b/backend/requirements.txt
index d4c365e..5d4c4b2 100644
--- a/backend/requirements.txt
+++ b/backend/requirements.txt
@@ -4,7 +4,7 @@ pydantic-settings>=2.5
 httpx>=0.27
 uvicorn[standard]>=0.32
 # LangChain + vector store + PDFs
-langchain>=0.3.0
+langchain>=1.2.15
 langchain-core>=0.3.0
 langchain-community>=0.3.0
 langchain-openai>=0.2.0