diff --git a/changelog.d/12435.misc b/changelog.d/12435.misc
new file mode 100644
index 000000000000..3a6845257388
--- /dev/null
+++ b/changelog.d/12435.misc
@@ -0,0 +1 @@
+Enable certificate checking during complement tests.
diff --git a/docker/complement/conf-workers/workers-shared.yaml b/docker/complement/conf-workers/workers-shared.yaml
index cdadb736f6ff..8b6987037715 100644
--- a/docker/complement/conf-workers/workers-shared.yaml
+++ b/docker/complement/conf-workers/workers-shared.yaml
@@ -7,11 +7,6 @@ bcrypt_rounds: 4
 
 ## Federation ##
 
-# disable verification of federation certificates
-#
-# TODO: Figure out why this is still needed even though we are making use of the custom CA
-federation_verify_certificates: false
-
 # trust certs signed by Complement's CA
 federation_custom_ca_list:
 - /complement/ca/ca.crt
diff --git a/docker/complement/conf/homeserver.yaml b/docker/complement/conf/homeserver.yaml
index be53c4aa2e33..c9d6a312401a 100644
--- a/docker/complement/conf/homeserver.yaml
+++ b/docker/complement/conf/homeserver.yaml
@@ -41,13 +41,6 @@ database:
 
 ## Federation ##
 
-
-# disable verification of federation certificates
-#
-# TODO: this is temporary; see
-# https://github.com/matrix-org/synapse/issues/11803
-federation_verify_certificates: false
-
 # trust certs signed by the complement CA
 federation_custom_ca_list:
 - /complement/ca/ca.crt