diff --git a/backend/requirements.txt b/backend/requirements.txt
index 9c34c92..e1b760c 100644
--- a/backend/requirements.txt
+++ b/backend/requirements.txt
@@ -1,6 +1,7 @@
 # S0 backend requirements (pinned, no ORM)
 fastapi==0.115.2
 uvicorn[standard]==0.30.6
+python-multipart==0.0.9
 pytest==8.3.3
 httpx==0.27.2
 cryptography==43.0.1