diff --git a/pkgs/development/ocaml-modules/spacetime_lib/default.nix b/pkgs/development/ocaml-modules/spacetime_lib/default.nix
index 009b2ce3261..442d06e4f69 100644
--- a/pkgs/development/ocaml-modules/spacetime_lib/default.nix
+++ b/pkgs/development/ocaml-modules/spacetime_lib/default.nix
@@ -1,4 +1,7 @@
-{ lib, fetchFromGitHub, buildDunePackage, owee }:
+{ lib, fetchFromGitHub, buildDunePackage, ocaml, owee }:
+
+lib.throwIfNot (lib.versionAtLeast "4.12" ocaml.version)
+  "spacetime_lib is not available for OCaml ${ocaml.version}"
 
 buildDunePackage rec {
   pname = "spacetime_lib";