diff --git a/changelog.d/12818.misc b/changelog.d/12818.misc
new file mode 100644
index 0000000000..2f9dacc21d
--- /dev/null
+++ b/changelog.d/12818.misc
@@ -0,0 +1 @@
+Remove Caddy from the Synapse workers image used in Complement.
\ No newline at end of file
diff --git a/docker/complement/SynapseWorkers.Dockerfile b/docker/complement/SynapseWorkers.Dockerfile
index 9a4438e730..99a09cbc2b 100644
--- a/docker/complement/SynapseWorkers.Dockerfile
+++ b/docker/complement/SynapseWorkers.Dockerfile
@@ -6,12 +6,6 @@
 # https://github.com/matrix-org/synapse/blob/develop/docker/README-testing.md#testing-with-postgresql-and-single-or-multi-process-synapse
 FROM matrixdotorg/synapse-workers
 
-# Download a caddy server to stand in front of nginx and terminate TLS using Complement's
-# custom CA.
-# We include this near the top of the file in order to cache the result.
-RUN curl -OL "https://github.com/caddyserver/caddy/releases/download/v2.3.0/caddy_2.3.0_linux_amd64.tar.gz" && \
-  tar xzf caddy_2.3.0_linux_amd64.tar.gz && rm caddy_2.3.0_linux_amd64.tar.gz && mv caddy /root
-
 # Install postgresql
 RUN apt-get update && \
   DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends -y postgresql-13
@@ -31,16 +25,12 @@ COPY conf-workers/workers-shared.yaml /conf/workers/shared.yaml
 
 WORKDIR /data
 
-# Copy the caddy config
-COPY conf-workers/caddy.complement.json /root/caddy.json
-
 COPY conf-workers/postgres.supervisord.conf /etc/supervisor/conf.d/postgres.conf
-COPY conf-workers/caddy.supervisord.conf /etc/supervisor/conf.d/caddy.conf
 
 # Copy the entrypoint
 COPY conf-workers/start-complement-synapse-workers.sh /
 
-# Expose caddy's listener ports
+# Expose nginx's listener ports
 EXPOSE 8008 8448
 
 ENTRYPOINT ["/start-complement-synapse-workers.sh"]
diff --git a/docker/complement/conf-workers/caddy.complement.json b/docker/complement/conf-workers/caddy.complement.json
deleted file mode 100644
index 09e2136af2..0000000000
--- a/docker/complement/conf-workers/caddy.complement.json
+++ /dev/null
@@ -1,72 +0,0 @@
-{
-    "apps": {
-      "http": {
-        "servers": {
-          "srv0": {
-            "listen": [
-              ":8448"
-            ],
-            "routes": [
-              {
-                "match": [
-                  {
-                    "host": [
-                      "{{ server_name }}"
-                    ]
-                  }
-                ],
-                "handle": [
-                  {
-                    "handler": "subroute",
-                    "routes": [
-                      {
-                        "handle": [
-                          {
-                            "handler": "reverse_proxy",
-                            "upstreams": [
-                              {
-                                "dial": "localhost:8008"
-                              }
-                            ]
-                          }
-                        ]
-                      }
-                    ]
-                  }
-                ],
-                "terminal": true
-              }
-            ]
-          }
-        }
-      },
-      "tls": {
-        "automation": {
-          "policies": [
-            {
-              "subjects": [
-                "{{ server_name }}"
-              ],
-              "issuers": [
-                {
-                  "module": "internal"
-                }
-              ],
-              "on_demand": true
-            }
-          ]
-        }
-      },
-      "pki": {
-        "certificate_authorities": {
-          "local": {
-            "name": "Complement CA",
-            "root": {
-              "certificate": "/complement/ca/ca.crt",
-              "private_key": "/complement/ca/ca.key"
-            }
-          }
-        }
-      }
-    }
-  }
diff --git a/docker/complement/conf-workers/caddy.supervisord.conf b/docker/complement/conf-workers/caddy.supervisord.conf
deleted file mode 100644
index d9ddb51dac..0000000000
--- a/docker/complement/conf-workers/caddy.supervisord.conf
+++ /dev/null
@@ -1,7 +0,0 @@
-[program:caddy]
-command=/usr/local/bin/prefix-log /root/caddy run --config /root/caddy.json
-autorestart=unexpected
-stdout_logfile=/dev/stdout
-stdout_logfile_maxbytes=0
-stderr_logfile=/dev/stderr
-stderr_logfile_maxbytes=0
diff --git a/docker/complement/conf-workers/start-complement-synapse-workers.sh b/docker/complement/conf-workers/start-complement-synapse-workers.sh
index b9a6b55bbe..a10b57a53f 100755
--- a/docker/complement/conf-workers/start-complement-synapse-workers.sh
+++ b/docker/complement/conf-workers/start-complement-synapse-workers.sh
@@ -9,9 +9,6 @@ function log {
     echo "$d $@"
 }
 
-# Replace the server name in the caddy config
-sed -i "s/{{ server_name }}/${SERVER_NAME}/g" /root/caddy.json
-
 # Set the server name of the homeserver
 export SYNAPSE_SERVER_NAME=${SERVER_NAME}
 
@@ -39,6 +36,21 @@ export SYNAPSE_WORKER_TYPES="\
     appservice, \
     pusher"
 
+
+# Generate a TLS key, then generate a certificate by having Complement's CA sign it
+# Note that both the key and certificate are in PEM format (not DER).
+openssl genrsa -out /conf/server.tls.key 2048
+
+openssl req -new -key /conf/server.tls.key -out /conf/server.tls.csr \
+  -subj "/CN=${SERVER_NAME}"
+
+openssl x509 -req -in /conf/server.tls.csr \
+  -CA /complement/ca/ca.crt -CAkey /complement/ca/ca.key -set_serial 1 \
+  -out /conf/server.tls.crt
+
+export SYNAPSE_TLS_CERT=/conf/server.tls.crt
+export SYNAPSE_TLS_KEY=/conf/server.tls.key
+
 # Run the script that writes the necessary config files and starts supervisord, which in turn
 # starts everything else
 exec /configure_workers_and_start.py
diff --git a/docker/conf-workers/nginx.conf.j2 b/docker/conf-workers/nginx.conf.j2
index 1081979e06..967fc65e79 100644
--- a/docker/conf-workers/nginx.conf.j2
+++ b/docker/conf-workers/nginx.conf.j2
@@ -9,6 +9,22 @@ server {
     listen 8008;
     listen [::]:8008;
 
+    {% if tls_cert_path is not none and tls_key_path is not none %}
+        listen 8448 ssl;
+        listen [::]:8448 ssl;
+
+        ssl_certificate {{ tls_cert_path }};
+        ssl_certificate_key {{ tls_key_path }};
+
+        # Some directives from cipherlist.eu (fka cipherli.st):
+        ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3;
+        ssl_prefer_server_ciphers on;
+        ssl_ciphers "EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH";
+        ssl_ecdh_curve secp384r1; # Requires nginx >= 1.1.0
+        ssl_session_cache shared:SSL:10m;
+        ssl_session_tickets off; # Requires nginx >= 1.5.9
+    {% endif %}
+
     server_name localhost;
 
     # Nginx by default only allows file uploads up to 1M in size
diff --git a/docker/configure_workers_and_start.py b/docker/configure_workers_and_start.py
index b2b7938ae8..f46b9b675e 100755
--- a/docker/configure_workers_and_start.py
+++ b/docker/configure_workers_and_start.py
@@ -21,6 +21,9 @@
 #   * SYNAPSE_REPORT_STATS: Whether to report stats.
 #   * SYNAPSE_WORKER_TYPES: A comma separated list of worker names as specified in WORKER_CONFIG
 #         below. Leave empty for no workers, or set to '*' for all possible workers.
+#   * SYNAPSE_TLS_CERT: Path to a TLS certificate in PEM format.
+#   * SYNAPSE_TLS_KEY: Path to a TLS key. If this and SYNAPSE_TLS_CERT are specified,
+#         Nginx will be configured to serve TLS on port 8448.
 #
 # NOTE: According to Complement's ENTRYPOINT expectations for a homeserver image (as defined
 # in the project's README), this script may be run multiple times, and functionality should
@@ -501,6 +504,8 @@ def generate_worker_files(
         "/etc/nginx/conf.d/matrix-synapse.conf",
         worker_locations=nginx_location_config,
         upstream_directives=nginx_upstream_config,
+        tls_cert_path=os.environ.get("SYNAPSE_TLS_CERT"),
+        tls_key_path=os.environ.get("SYNAPSE_TLS_KEY"),
     )
 
     # Supervisord config