diff --git a/.ci-macosx.sh b/.ci-macosx.sh
index ea6d44cb1..b793b0d7a 100644
--- a/.ci-macosx.sh
+++ b/.ci-macosx.sh
@@ -6,7 +6,7 @@ brew update
 brew install pkg-config
 brew install opam
 brew install libev
-opam init -y --compiler=4.05.0
+opam init -y --compiler=4.12.0
 eval $(opam env)
 
 opam install -y -j 2 . --deps-only --locked
diff --git a/Dockerfile b/Dockerfile
index c9e6079b7..8853da4d0 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ocaml/opam2:alpine as compilation
+FROM ocaml/opam:alpine-3.13-ocaml-4.12 as compilation
 LABEL Description="learn-ocaml building" Vendor="OCamlPro"
 
 WORKDIR /home/opam/learn-ocaml
diff --git a/Dockerfile.test-client b/Dockerfile.test-client
index ee7c49a13..32345200a 100644
--- a/Dockerfile.test-client
+++ b/Dockerfile.test-client
@@ -1,7 +1,7 @@
 # This Dockerfile is useful for testing purposes
 # to ensure learn-ocaml-client can be built alone from learn-ocaml-client.opam
 
-FROM ocaml/opam:alpine-3.13-ocaml-4.05 as compilation
+FROM ocaml/opam:alpine-3.13-ocaml-4.12 as compilation
 LABEL Description="learn-ocaml building" Vendor="OCamlPro"
 
 WORKDIR learn-ocaml
@@ -13,7 +13,7 @@ RUN sudo chown -R opam:nogroup .
 ENV OPAMYES true
 RUN echo 'archive-mirrors: [ "https://opam.ocaml.org/cache" ]' >> ~/.opam/config \
   && opam repository set-url default http://opam.ocaml.org \
-  && opam switch 4.05 \
+  && opam switch 4.12 \
   && echo 'pre-session-commands: [ "sudo" "apk" "add" depexts ]' >> ~/.opam/config \
   && opam pin add -n -y -k path learn-ocaml-client . \
   && opam install learn-ocaml-client --deps-only
diff --git a/scripts/static-build.sh b/scripts/static-build.sh
index adbddf9a5..ea9e6c5a0 100755
--- a/scripts/static-build.sh
+++ b/scripts/static-build.sh
@@ -10,7 +10,7 @@ cd $(dirname "$0")/..
 set -o pipefail
 git ls-files -z | xargs -0 tar c | \
   docker run --rm -i \
-    ocamlpro/ocaml:4.05 \
+    ocamlpro/ocaml:4.12 \
     sh -uexc \
       'tar x >&2 &&
        sudo apk add openssl-libs-static >&2 &&