diff --git a/pkgs/development/ocaml-modules/cstruct/sexp.nix b/pkgs/development/ocaml-modules/cstruct/sexp.nix
index 9a1ef0dd301..d4b311181d5 100644
--- a/pkgs/development/ocaml-modules/cstruct/sexp.nix
+++ b/pkgs/development/ocaml-modules/cstruct/sexp.nix
@@ -4,12 +4,12 @@ if !lib.versionAtLeast (cstruct.version or "1") "3"
 then cstruct
 else
 
-buildDunePackage {
+buildDunePackage rec {
 	pname = "cstruct-sexp";
 	inherit (cstruct) version src meta;
 
 	doCheck = true;
-	buildInputs = [ alcotest ];
+	checkInputs = lib.optional doCheck alcotest;
 
 	propagatedBuildInputs = [ cstruct sexplib ];
 }