diff --git a/backend/src/langs.ts b/backend/src/langs.ts
index b56c0ab..b64d98f 100644
--- a/backend/src/langs.ts
+++ b/backend/src/langs.ts
@@ -528,6 +528,23 @@ Put milk chocolate into the mixing bowl.
 Liquefy contents of the mixing bowl.
 Pour contents of the mixing bowl into the baking dish.
 Refrigerate for 1 hour.
+`,
+  },
+  clean: {
+    aliases: ["icl", "clm"],
+    name: "Clean",
+    main: "main.icl",
+    compile: "clm main -o main",
+    run: "./main",
+    template: `module main
+
+import StdEnv
+
+Start world
+  #(console, world) = stdio world
+  #console = fwrites "Hello, world!\\n" console
+  #(ok, world) = fclose console world
+  = world
 `,
   },
   clojure: {
diff --git a/scripts/docker-install-phase6.bash b/scripts/docker-install-phase6.bash
index 4c30a43..24a4ff6 100755
--- a/scripts/docker-install-phase6.bash
+++ b/scripts/docker-install-phase6.bash
@@ -31,6 +31,16 @@ pushd /opt/cat >/dev/null
 npm install
 popd >/dev/null
 
+# Clean
+wget -nv "$(curl -sSL https://clean.cs.ru.nl/Download_Clean | grep linux/clean | grep -F 64.tar.gz | grep -Eo "https://[^>]+\.tar\.gz")"
+mkdir /opt/clean
+tar -xf clean*_64.tar.gz -C /opt/clean --strip-components=1
+pushd /opt/clean >/dev/null
+make
+popd >/dev/null
+ln -s /opt/clean/bin/clm /usr/local/bin/
+rm clean*_64.tar.gz
+
 # Erlang
 git clone https://github.com/erlang-ls/erlang_ls.git
 pushd erlang_ls >/dev/null