diff --git a/changelog.d/12819.misc b/changelog.d/12819.misc
new file mode 100644
index 0000000000..7a03102a63
--- /dev/null
+++ b/changelog.d/12819.misc
@@ -0,0 +1 @@
+Add Complement's shared registration secret to the Complement worker image. This fixes tests that depend on it.
\ No newline at end of file
diff --git a/docker/complement/conf-workers/workers-shared.yaml b/docker/complement/conf-workers/workers-shared.yaml
index 86ee11ecd0..cd7b50c65c 100644
--- a/docker/complement/conf-workers/workers-shared.yaml
+++ b/docker/complement/conf-workers/workers-shared.yaml
@@ -5,6 +5,12 @@ enable_registration: true
 enable_registration_without_verification: true
 bcrypt_rounds: 4
 
+## Registration ##
+
+# Needed by Complement to register admin users
+# DO NOT USE in a production configuration! This should be a random secret.
+registration_shared_secret: complement
+
 ## Federation ##
 
 # trust certs signed by Complement's CA