diff --git a/buildjob b/buildjob
index 366b4cdeefee7e9e551ee3d87c9ccd0c3ea4d394..e1827113840a3a3d570fb712550f5ba67732019a 100755
--- a/buildjob
+++ b/buildjob
@@ -63,7 +63,7 @@ fi
 
 # Prepare
 # We pin a particular dune version to avoid constant rebuilds (dune is required by coq, and gets updated a lot).
-. ci/prepare-opam.sh dune version 3.15.3 $OPAM_PINS # deliberately not quoted
+. ci/prepare-opam.sh dune version 3.13.1 $OPAM_PINS # deliberately not quoted
 env | egrep '^(CI_BUILD_REF|CI_RUNNER)' > build-env.txt
 
 if [[ -n "$MANGLE_NAMES" ]]; then