diff --git a/roles/custom/matrix-synapse-auto-compressor/templates/env.j2 b/roles/custom/matrix-synapse-auto-compressor/templates/env.j2
index e0e68511f..85f18066d 100644
--- a/roles/custom/matrix-synapse-auto-compressor/templates/env.j2
+++ b/roles/custom/matrix-synapse-auto-compressor/templates/env.j2
@@ -1,4 +1,6 @@
 POSTGRES_LOCATION={{ matrix_synapse_auto_compressor_environment_variable_postgres_location }}
+
+# PG-prefixed variables below are for the matrix-synapse-auto-compressor-fix.sh script
 PGHOST={{ matrix_synapse_auto_compressor_database_hostname }}
 PGDATABASE={{ matrix_synapse_auto_compressor_database_name }}
 PGUSER={{ matrix_synapse_auto_compressor_database_username }}