diff --git a/backend/docker/engine.Dockerfile b/backend/docker/engine.Dockerfile
index 58ccd481..345cbeb4 100644
--- a/backend/docker/engine.Dockerfile
+++ b/backend/docker/engine.Dockerfile
@@ -43,6 +43,10 @@ COPY ./utils/ ./utils/
 # engine.py -> backend.apis.GoogleSolarApi -> infrastructure.solar; without this
 # the lambda fails at init with "No module named 'infrastructure'".
 COPY ./infrastructure/ ./infrastructure/
+# backend.app.db.models.portfolio re-exports PortfolioGoal from
+# domain.modelling.portfolio_goal (ADR-0017 amendment); without this the lambda
+# fails at init with "No module named 'domain'".
+COPY ./domain/ ./domain/
 COPY ./etl/epc/ ./etl/epc/
 COPY ./etl/epc_clean/ ./etl/epc_clean/
 COPY ./etl/bill_savings/ ./etl/bill_savings/