diff --git a/scripts/install_build_deps.sh b/scripts/install_build_deps.sh
index 143697090..3d9eedb46 100755
--- a/scripts/install_build_deps.sh
+++ b/scripts/install_build_deps.sh
@@ -22,7 +22,7 @@ if [ ! -d "$src_dir/_opam" ] ; then
     exit 1
 fi
 
-eval $(opam env)
+eval $(opam env --shell=sh)
 
 if [ "$(ocaml -vnum)" != "$ocaml_version" ]; then
     opam install --unlock-base ocaml-base-compiler.$ocaml_version