diff --git a/roles/custom/matrix-synapse/defaults/main.yml b/roles/custom/matrix-synapse/defaults/main.yml
index a5c7106ff..f809f60e3 100644
--- a/roles/custom/matrix-synapse/defaults/main.yml
+++ b/roles/custom/matrix-synapse/defaults/main.yml
@@ -70,9 +70,10 @@ matrix_synapse_container_image_customizations_templates_git_repository_keyscan_h
 matrix_synapse_container_image_customizations_dockerfile_body_custom: ''
 
 matrix_synapse_docker_image: "{{ matrix_synapse_docker_image_name_prefix }}matrixdotorg/synapse:{{ matrix_synapse_docker_image_tag }}"
-matrix_synapse_docker_image_name_prefix: "{{ 'localhost/' if matrix_synapse_container_image_self_build else matrix_container_global_registry_prefix }}"
+matrix_synapse_docker_image_name_prefix: "{{ 'localhost/' if matrix_synapse_container_image_self_build else matrix_synapse_docker_image_registry_prefix }}"
 matrix_synapse_docker_image_tag: "{{ matrix_synapse_version }}"
 matrix_synapse_docker_image_force_pull: "{{ matrix_synapse_docker_image.endswith(':latest') }}"
+matrix_synapse_docker_image_registry_prefix: "{{ matrix_container_global_registry_prefix }}"
 
 # matrix_synapse_docker_image_customized is the name of the locally built Synapse image
 # which adds various customizations on top of the original (upstream) Synapse image.