diff --git a/Dockerfile b/Dockerfile
index e3d36de..fcc5b3c 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -4,7 +4,7 @@
 ARG NUM_PARALLEL_JOBS=1
 
 COPY . /source
-RUN cd /source && make -j${NUM_PARALLEL_JOBS} database
+RUN cd /source && make -j${NUM_PARALLEL_JOBS} --output-sync=target --warn-undefined-variables database
 RUN find /source/database -mindepth 1 -maxdepth 1 -type d -exec /source/htmlgen/htmlgen.py --settings={}/settings.sh --output=/output/html \;
 RUN mkdir -p /output/raw && find /source/database -mindepth 1 -maxdepth 1 -type d -exec cp -R {} /output/raw \;