diff --git a/prepare-opam.sh b/prepare-opam.sh
index 475def8d673ee204b5e4ea9c3ab0aea453a4ba8c..6d2c4efc27b195a3ca1640bea15ac5dbb34944e3 100644
--- a/prepare-opam.sh
+++ b/prepare-opam.sh
@@ -70,7 +70,7 @@ fi
 
 # Install build-dependencies.
 echo_color "$BOLDGREEN" "[prepare-opam] Installing build-dependencies"
-make build-dep OPAMFLAGS=-y
+make build-dep OPAMFLAGS="-y --use-internal-solver"
 echo
 
 # done