diff --git a/sys-cluster/clusteringsuite/clusteringsuite-2.6.9-r3.ebuild b/sys-cluster/clusteringsuite/clusteringsuite-2.6.9-r3.ebuild
index 82532ed993..5ae7734f0c 100644
--- a/sys-cluster/clusteringsuite/clusteringsuite-2.6.9-r3.ebuild
+++ b/sys-cluster/clusteringsuite/clusteringsuite-2.6.9-r3.ebuild
@@ -37,7 +37,7 @@ RDEPEND="
 	mpi? ( virtual/mpi )
 	muster? ( sys-cluster/muster )
 	treedbscan? (
-		dev-libs/boost:=[threads]
+		dev-libs/boost:=[threads(+)]
 		dev-libs/gmp
 		dev-libs/mpfr
 		sci-mathematics/cgal[shared(-)]