diff --git a/dev-ml/num/num-1.5.ebuild b/dev-ml/num/num-1.5.ebuild
index baaacdcf8f0ea..f8dc825a611de 100644
--- a/dev-ml/num/num-1.5.ebuild
+++ b/dev-ml/num/num-1.5.ebuild
@@ -20,6 +20,10 @@ BDEPEND="${RDEPEND}"
 DEPEND="dev-ml/findlib:=[ocamlopt?]"
 
 src_compile() {
+	emake CFLAGS="${CFLAGS}" \
+		NATDYNLINK="$(usex ocamlopt true false)" \
+		NATIVE_COMPILER="$(usex ocamlopt true false)" \
+		-C src num_top.ml
 	emake CFLAGS="${CFLAGS}" \
 		NATDYNLINK="$(usex ocamlopt true false)" \
 		NATIVE_COMPILER="$(usex ocamlopt true false)"