diff --git a/ocaml-tplib.spec b/ocaml-tplib.spec
index 1d8ab15..966e944 100644
--- a/ocaml-tplib.spec
+++ b/ocaml-tplib.spec
@@ -25,6 +25,7 @@ BuildRequires:  ocaml
 BuildRequires:  ocaml-ocamlbuild
 BuildRequires:  ocaml-camlidl-devel
 BuildRequires:  ocaml-findlib-devel
+BuildRequires:  ocaml-num-devel
 BuildRequires:  ocaml-ocamldoc
 BuildRequires:  ocaml-zarith-devel