diff --git a/bench.Dockerfile b/bench.Dockerfile
index 9b39584..01de776 100644
--- a/bench.Dockerfile
+++ b/bench.Dockerfile
@@ -1,6 +1,7 @@
 FROM ocaml/opam:debian-ocaml-5.1
 RUN sudo ln -sf /usr/bin/opam-2.1 /usr/bin/opam
 WORKDIR bench-dir
+RUN sudo chown opam .
 COPY *.opam ./
 RUN opam remote add origin https://github.com/ocaml/opam-repository.git && \
     opam update