diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 43993e3e093..c3eafbb56e0 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -1980,7 +1980,7 @@ let
 
   ocaml_3_11_1 = callPackage ../development/compilers/ocaml/3.11.1.nix { };
 
-  ocaml_3_12_0 = callPackage ../development/compilers/ocaml/3.12.0.nix { };
+  ocaml_3_12_0 = lowPrio (callPackage ../development/compilers/ocaml/3.12.0.nix { });
 
   mkOcamlPackages = ocaml: self: let callPackage = newScope self; in rec {
     inherit ocaml;