diff --git a/changelog.d/10039.misc b/changelog.d/10039.misc
new file mode 100644
index 000000000..8855f141d
--- /dev/null
+++ b/changelog.d/10039.misc
@@ -0,0 +1 @@
+Fix running complement tests with Synapse workers.
diff --git a/docker/configure_workers_and_start.py b/docker/configure_workers_and_start.py
index 4be6afc65..1d22a4d57 100755
--- a/docker/configure_workers_and_start.py
+++ b/docker/configure_workers_and_start.py
@@ -184,18 +184,18 @@ stderr_logfile_maxbytes=0
 """
 
 NGINX_LOCATION_CONFIG_BLOCK = """
-    location ~* {endpoint} {
+    location ~* {endpoint} {{
         proxy_pass {upstream};
         proxy_set_header X-Forwarded-For $remote_addr;
         proxy_set_header X-Forwarded-Proto $scheme;
         proxy_set_header Host $host;
-    }
+    }}
 """
 
 NGINX_UPSTREAM_CONFIG_BLOCK = """
-upstream {upstream_worker_type} {
+upstream {upstream_worker_type} {{
 {body}
-}
+}}
 """
 
 
diff --git a/scripts-dev/complement.sh b/scripts-dev/complement.sh
index 1612ab522..004396467 100755
--- a/scripts-dev/complement.sh
+++ b/scripts-dev/complement.sh
@@ -10,6 +10,9 @@
 # checkout by setting the COMPLEMENT_DIR environment variable to the
 # filepath of a local Complement checkout.
 #
+# By default Synapse is run in monolith mode. This can be overridden by
+# setting the WORKERS environment variable.
+#
 # A regular expression of test method names can be supplied as the first
 # argument to the script. Complement will then only run those tests. If
 # no regex is supplied, all tests are run. For example;
@@ -32,10 +35,26 @@ if [[ -z "$COMPLEMENT_DIR" ]]; then
   echo "Checkout available at 'complement-master'"
 fi
 
+# If we're using workers, modify the docker files slightly.
+if [[ -n "$WORKERS" ]]; then
+  BASE_IMAGE=matrixdotorg/synapse-workers
+  BASE_DOCKERFILE=docker/Dockerfile-workers
+  export COMPLEMENT_BASE_IMAGE=complement-synapse-workers
+  COMPLEMENT_DOCKERFILE=SynapseWorkers.Dockerfile
+  # And provide some more configuration to complement.
+  export COMPLEMENT_CA=true
+  export COMPLEMENT_VERSION_CHECK_ITERATIONS=500
+else
+  BASE_IMAGE=matrixdotorg/synapse
+  BASE_DOCKERFILE=docker/Dockerfile
+  export COMPLEMENT_BASE_IMAGE=complement-synapse
+  COMPLEMENT_DOCKERFILE=Synapse.Dockerfile
+fi
+
 # Build the base Synapse image from the local checkout
-docker build -t matrixdotorg/synapse -f docker/Dockerfile .
+docker build -t $BASE_IMAGE -f "$BASE_DOCKERFILE" .
 # Build the Synapse monolith image from Complement, based on the above image we just built
-docker build -t complement-synapse -f "$COMPLEMENT_DIR/dockerfiles/Synapse.Dockerfile" "$COMPLEMENT_DIR/dockerfiles"
+docker build -t $COMPLEMENT_BASE_IMAGE -f "$COMPLEMENT_DIR/dockerfiles/$COMPLEMENT_DOCKERFILE" "$COMPLEMENT_DIR/dockerfiles"
 
 cd "$COMPLEMENT_DIR"
 
@@ -46,4 +65,4 @@ if [[ -n "$1" ]]; then
 fi
 
 # Run the tests!
-COMPLEMENT_BASE_IMAGE=complement-synapse go test -v -tags synapse_blacklist,msc2946,msc3083 -count=1 $EXTRA_COMPLEMENT_ARGS ./tests
+go test -v -tags synapse_blacklist,msc2946,msc3083 -count=1 $EXTRA_COMPLEMENT_ARGS ./tests