diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 06b6c85bca4b7792dca59787b8a0524d9571ed84..9c9ecb701a0cacd421969f950aea33019b48cd8d 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -51,6 +51,7 @@ build-coq.8.9.0:
     OPAM_PINS: "coq version 8.9.0"
     OPAM_PKG: "coq-iris"
     DOC_DIR: "coqdoc@center.mpi-sws.org:iris"
+    DOC_OPTS: "--external https://plv.mpi-sws.org/coqdoc/stdpp/ stdpp"
     TIMING_CONF: "coq-8.9.0"
   tags:
   - fp-timing