diff --git a/src/build-deps.sh b/src/build-deps.sh
index bbfd9c3cf..821186320 100644
--- a/src/build-deps.sh
+++ b/src/build-deps.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
+opam switch create .. ocaml-base-compiler.4.06.1
+eval $(opam env)
 vendors/opam-repository-tools/rewrite-local-opam-repository.sh
 opam repository add localrepo "file://$PWD/vendors/ligo-opam-repository-local-generated/"
-opam install ocp-indent merlin alcotest-lwt crowbar
+opam install -y ocp-indent merlin alcotest-lwt crowbar
 opam user-setup install
 opam install -y --build-test --deps-only ./src/ 
diff --git a/src/install.sh b/src/install.sh
index 99d86d003..78e7c42e5 100644
--- a/src/install.sh
+++ b/src/install.sh
@@ -1,6 +1,6 @@
-add-apt-repository ppa:avsm/ppa
-apt update
-apt-get install opam mercurial darcs make m4 gcc libev-dev libgmp-dev pkg-config libhidapi-dev
-opam init --bare
-y
-y
+#! /bin/sh
+sudo add-apt-repository -y ppa:avsm/ppa
+sudo apt-get update
+sudo apt-get install -y opam mercurial darcs make m4 gcc libev-dev libgmp-dev pkg-config libhidapi-dev
+opam init --bare -a
+