diff --git a/backend/requirements.txt b/backend/requirements.txt
index 3fedfef6..4f02f1b2 100644
--- a/backend/requirements.txt
+++ b/backend/requirements.txt
@@ -40,5 +40,5 @@ torch>=2.12.0,<3.0
 # sentence-transformers was the all-MiniLM embedder dep (rejected per ADR-017 — generic English LM
 # produces biologically invalid embeddings for amino acid sequences).
 lancedb>=0.30.2,<1.0
-transformers>=4.30,<5.0
+transformers>=5.9.0,<6.0
 pyarrow>=24.0.0,<25.0