diff --git a/pkgs/development/compilers/ocaml/4.12.nix b/pkgs/development/compilers/ocaml/4.12.nix
new file mode 100644
index 0000000000000..9fa5d62423cc5
--- /dev/null
+++ b/pkgs/development/compilers/ocaml/4.12.nix
@@ -0,0 +1,9 @@
+import ./generic.nix {
+  major_version = "4";
+  minor_version = "12";
+  patch_version = "0-alpha1";
+  src = fetchTarball {
+    url = "http://caml.inria.fr/pub/distrib/ocaml-4.12/ocaml-4.12.0~alpha1.tar.xz";
+    sha256 = "1p9nnj7l43b697b6bm767znbf1h0s2lyc1qb8izr1vfpsmnm11ws";
+  };
+}
diff --git a/pkgs/top-level/ocaml-packages.nix b/pkgs/top-level/ocaml-packages.nix
index 235ffb67c9b0e..64a23c21fc306 100644
--- a/pkgs/top-level/ocaml-packages.nix
+++ b/pkgs/top-level/ocaml-packages.nix
@@ -1257,6 +1257,8 @@ in let inherit (pkgs) callPackage; in rec
 
   ocamlPackages_4_11 = mkOcamlPackages (callPackage ../development/compilers/ocaml/4.11.nix { });
 
+  ocamlPackages_4_12 = mkOcamlPackages (callPackage ../development/compilers/ocaml/4.12.nix { });
+
   ocamlPackages_latest = ocamlPackages_4_11;
 
   ocamlPackages = ocamlPackages_4_10;