diff --git a/CHANGES.md b/CHANGES.md
index dec2630130..75dc5fa893 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,9 @@
+Synapse 1.21.1 (2020-10-13)
+===========================
+
+This release fixes a regression in v1.21.0 that prevented debian packages from being built.
+It is otherwise identical to v1.21.0.
+
 Synapse 1.21.0 (2020-10-12)
 ===========================
 
diff --git a/debian/build_virtualenv b/debian/build_virtualenv
index 4c9aabcac3..cbdde93f96 100755
--- a/debian/build_virtualenv
+++ b/debian/build_virtualenv
@@ -42,7 +42,7 @@ dh_virtualenv \
     --preinstall="mock" \
     --extra-pip-arg="--no-cache-dir" \
     --extra-pip-arg="--compile" \
-    --extras="all,systemd"
+    --extras="all,systemd,test"
 
 PACKAGE_BUILD_DIR="debian/matrix-synapse-py3"
 VIRTUALENV_DIR="${PACKAGE_BUILD_DIR}${DH_VIRTUALENV_INSTALL_ROOT}/matrix-synapse"
diff --git a/debian/changelog b/debian/changelog
index a08782f587..eeafd4f50a 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,13 @@
+matrix-synapse-py3 (1.21.1) stable; urgency=medium
+
+  [ Synapse Packaging team ]
+  * New synapse release 1.21.1.
+
+  [ Andrew Morgan ]
+  * Explicitly install "test" python dependencies.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 13 Oct 2020 10:24:13 +0100
+
 matrix-synapse-py3 (1.21.0) stable; urgency=medium
 
   * New synapse release 1.21.0.
diff --git a/synapse/__init__.py b/synapse/__init__.py
index 57f818125a..722b53a67d 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -48,7 +48,7 @@ try:
 except ImportError:
     pass
 
-__version__ = "1.21.0"
+__version__ = "1.21.1"
 
 if bool(os.environ.get("SYNAPSE_TEST_PATCH_LOG_CONTEXTS", False)):
     # We import here so that we don't have to install a bunch of deps when