diff --git a/debian/build_virtualenv b/debian/build_virtualenv

index 21caad90cc..68c8659953 100755
--- a/debian/build_virtualenv
+++ b/debian/build_virtualenv
@@ -33,13 +33,11 @@ esac
 # Use --builtin-venv to use the better `venv` module from CPython 3.4+ rather
 # than the 2/3 compatible `virtualenv`.
 
-# Pin pip to 20.3.4 to fix breakage in 21.0 on py3.5 (xenial)
-
 dh_virtualenv \
     --install-suffix "matrix-synapse" \
     --builtin-venv \
     --python "$SNAKE" \
-    --upgrade-pip-to="20.3.4" \
+    --upgrade-pip \
     --preinstall="lxml" \
     --preinstall="mock" \
     --extra-pip-arg="--no-cache-dir" \