diff --git a/scripts/install_build_deps.raw.sh b/scripts/install_build_deps.raw.sh
index 38034285e6a5d8c728aec374d2a3da0ed07c4170..e050691e828460564823cd7e7b6e4f28f2beb44f 100755
--- a/scripts/install_build_deps.raw.sh
+++ b/scripts/install_build_deps.raw.sh
@@ -18,7 +18,17 @@ export OPAMYES=${OPAMYES:=true}
 # Note that install_build_deps.sh calls install_build_deps.rust.sh
 # which checks whether Rust is installed with the right version and explains how
 # to install it if needed, so using opam depext is redundant anyway.
-opam depext conf-gmp conf-libev conf-pkg-config conf-hidapi ctypes-foreign conf-autoconf conf-libffi conf-zlib #conf-rust
+conf_packages="conf-gmp conf-libev conf-pkg-config conf-hidapi ctypes-foreign conf-autoconf conf-libffi conf-zlib" #conf-rust
+
+# Opam < 2.1 uses opam-depext as a plugin, later versions provide the option
+# `--depext-only`:
+case $(opam --version) in
+    2.0.* ) opam_depext_command="opam depext $conf_packages" ;;
+    * ) opam_depext_command="opam install --depext-only $conf_packages" ;;
+esac
+## ShellCheck does not fail when non-quoted variables are at the beginning
+## of a command:
+$opam_depext_command
 
 ## In an ideal world, `--with-test` should be present only when using
 ## `--dev`. But this would probably break the CI, so we postponed this
diff --git a/scripts/install_build_deps.sh b/scripts/install_build_deps.sh
index e378b4d9c98fba267f891ffd676898b33fe4e8e0..5461d84e74605283093da12e06ab1710bf83584d 100755
--- a/scripts/install_build_deps.sh
+++ b/scripts/install_build_deps.sh
@@ -80,7 +80,12 @@ fi
 # opam packages that depend on Rust.
 "$script_dir"/install_build_deps.rust.sh
 
-opam install --yes opam-depext
+# Opam < 2.1 requires opam-depext as a plugin, later versions include it
+# natively:
+case $(opam --version) in
+    2.0.* )
+        opam install --yes opam-depext ;;
+esac
 
 "$script_dir"/install_build_deps.raw.sh
 
diff --git a/scripts/update_opam_repo.sh b/scripts/update_opam_repo.sh
index bc3959da77bd230b1d8928df3c5e4117f765dd9b..15d91312977b2443a8f4d2698faf01eda821225f 100755
--- a/scripts/update_opam_repo.sh
+++ b/scripts/update_opam_repo.sh
@@ -88,8 +88,23 @@ done
 ## Filtering unrequired packages
 cd $tmp_dir
 git reset --hard "$full_opam_repository_tag"
+# Opam < 2.1 requires opam-depext as a plugin, later versions include it
+# natively:
+extra_warning=""
+case $(opam --version) in
+    2.0.* ) opam_depext_dep="opam-depext," ;;
+    * )
+        opam_depext_dep=""
+        extra_warning="
+WARNING you are using opam $(opam --version), your patch
+is potentially removing the opam 2.0.x dependency 'opam-depext', please
+make sure you are not removing it (for instance by editing the patch,
+fixing the resulting merge-request, or re-running with opam 2.0.x)."
+        ;;
+esac
+#shellcheck disable=SC2086
 OPAMSOLVERTIMEOUT=600 opam admin filter --yes --resolve \
-  $packages,ocaml,ocaml-base-compiler,odoc,opam-depext,js_of_ocaml-ppx,opam-ed
+  $packages,ocaml,ocaml-base-compiler,odoc,${opam_depext_dep}js_of_ocaml-ppx,opam-ed
 
 ## Adding useful compiler variants
 for variant in afl flambda fp spacetime ; do
@@ -117,4 +132,5 @@ echo
 echo "Wrote proposed update in: $target."
 echo 'Please add this patch to: `https://gitlab.com/tezos/opam-repository`'
 echo 'And update accordingly the commit hash in: `.gitlab/ci/templates.yml` and `scripts/version.sh`'
+echo "$extra_warning"
 echo
diff --git a/scripts/version.sh b/scripts/version.sh
index 40c7316af7f6a0fe949a56c4de63ca6cfe02618a..df6a495a6ed016612dc02eef4b92d3b40be34818 100755
--- a/scripts/version.sh
+++ b/scripts/version.sh
@@ -14,7 +14,7 @@
 ## with both the make and sh syntax
 
 export ocaml_version=4.12.1
-export opam_version=2.0
+export opam_version=2
 export recommended_rust_version=1.52.1
 
 ## full_opam_repository is a commit hash of the public OPAM repository, i.e.