diff --git a/containers/jug/dev.Dockerfile b/containers/jug/dev.Dockerfile
index 030704f8b4480c492657df537171c354b666df6a..22093fb4921903fe52637b524c224690b2c9798d 100644
--- a/containers/jug/dev.Dockerfile
+++ b/containers/jug/dev.Dockerfile
@@ -55,6 +55,7 @@ SHELL ["docker-shell"]
 RUN --mount=type=cache,target=/var/cache/spack-mirror                   \
     export PATH=$PATH:$SPACK_ROOT/bin                                   \
  && spack mirror add docker /var/cache/spack-mirror                     \
+ && spack buildcache update-index -d /var/cache/spack-mirror            \
  && spack mirror list
 
 ## Setup eic-spack buildcache mirrors (FIXME: leaks credentials into layer)