diff --git a/docker/Dockerfile b/docker/Dockerfile
index b4d67404..80ac0ede 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -29,7 +29,7 @@ WORKDIR /root
 RUN git clone https://github.com/KLayout/klayout
 WORKDIR /root/klayout
 RUN git checkout ${KLAYOUT_COMMIT}
-RUN ./build.sh -qt5 \
+RUN ./build.sh -qt5 -j 8 \
  && cp -r bin-release /usr/local/klayout
 RUN rm -rf /root/klayout