diff --git a/requirements.txt b/requirements.txt
index 1bf1ac764..dcfb4cb10 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,6 +2,7 @@ a2wsgi==1.10.8
 ansio==0.0.1
 docker==7.1.0
 duckduckgo-search==6.1.12
+pyreqwest-impersonate==0.5.3  # freeze nearest wheel-backed release; 0.5.5 is source-only
 faiss-cpu==1.11.0
 fastmcp==3.2.4
 fasta2a==0.5.0