diff --git a/pkgs/build-support/ocaml/topkg.nix b/pkgs/build-support/ocaml/topkg.nix
index 4326a61913e9..3648b19faad3 100644
--- a/pkgs/build-support/ocaml/topkg.nix
+++ b/pkgs/build-support/ocaml/topkg.nix
@@ -19,11 +19,10 @@
   ...
 }@args:
 
-lib.throwIf (args ? minimalOCamlVersion && lib.versionOlder ocaml.version args.minimalOCamlVersion)
-  "${pname}-${version} is not available for OCaml ${ocaml.version}"
-
-  stdenv.mkDerivation
-  (
+if (args ? minimalOCamlVersion && lib.versionOlder ocaml.version args.minimalOCamlVersion) then
+  throw "${pname}-${version} is not available for OCaml ${ocaml.version}"
+else
+  stdenv.mkDerivation (
     {
 
       dontAddStaticConfigureFlags = true;