diff --git a/graph/graphs/gen/holme_kim.go b/graph/graphs/gen/holme_kim.go
index 08529ccb..8f49995d 100644
--- a/graph/graphs/gen/holme_kim.go
+++ b/graph/graphs/gen/holme_kim.go
@@ -15,7 +15,7 @@ import (
 	"gonum.org/v1/gonum/stat/sampleuv"
 )
 
-// TunableClusteringScaleFree constructs a graph in the destination, dst, of order n.
+// TunableClusteringScaleFree constructs a subgraph in the destination, dst, of order n.
 // The graph is constructed successively starting from an m order graph with one node
 // having degree m-1. At each iteration of graph addition, one node is added with m
 // additional edges joining existing nodes with probability proportional to the nodes'
@@ -47,10 +47,11 @@ func TunableClusteringScaleFree(dst graph.UndirectedBuilder, n, m int, p float64
 
 	// Initial condition.
 	wt := make([]float64, n)
+	id := make([]int64, n)
 	for u := 0; u < m; u++ {
-		if dst.Node(int64(u)) == nil {
-			dst.AddNode(simple.Node(u))
-		}
+		un := dst.NewNode()
+		dst.AddNode(un)
+		id[u] = un.ID()
 		// We need to give equal probability for
 		// adding the first generation of edges.
 		wt[u] = 1
@@ -64,17 +65,24 @@ func TunableClusteringScaleFree(dst graph.UndirectedBuilder, n, m int, p float64
 
 	// Growth.
 	for v := m; v < n; v++ {
+		vn := dst.NewNode()
+		dst.AddNode(vn)
+		id[v] = vn.ID()
 		var u int
 	pa:
 		for i := 0; i < m; i++ {
 			// Triad formation.
 			if i != 0 && rnd() < p {
-				for _, w := range permute(graph.NodesOf(dst.From(int64(u))), rndN) {
+				// TODO(kortschak): Decide whether the node
+				// order in this input to permute should be
+				// sorted first to allow repeatable runs.
+				for _, w := range permute(graph.NodesOf(dst.From(id[u])), rndN) {
 					wid := w.ID()
-					if wid == int64(v) || dst.HasEdgeBetween(wid, int64(v)) {
+					if wid == id[v] || dst.HasEdgeBetween(wid, id[v]) {
 						continue
 					}
-					dst.SetEdge(simple.Edge{F: w, T: simple.Node(v)})
+
+					dst.SetEdge(dst.NewEdge(w, vn))
 					wt[wid]++
 					wt[v]++
 					continue pa
@@ -88,10 +96,10 @@ func TunableClusteringScaleFree(dst graph.UndirectedBuilder, n, m int, p float64
 				if !ok {
 					return errors.New("gen: depleted distribution")
 				}
-				if u == v || dst.HasEdgeBetween(int64(u), int64(v)) {
+				if u == v || dst.HasEdgeBetween(id[u], id[v]) {
 					continue
 				}
-				dst.SetEdge(simple.Edge{F: simple.Node(u), T: simple.Node(v)})
+				dst.SetEdge(dst.NewEdge(dst.Node(id[u]), vn))
 				wt[u]++
 				wt[v]++
 				break
diff --git a/graph/graphs/gen/holme_kim_test.go b/graph/graphs/gen/holme_kim_test.go
index c25e1985..443599d5 100644
--- a/graph/graphs/gen/holme_kim_test.go
+++ b/graph/graphs/gen/holme_kim_test.go
@@ -15,10 +15,15 @@ func TestTunableClusteringScaleFree(t *testing.T) {
 		for m := 0; m < n; m++ {
 			for p := 0.; p <= 1; p += 0.1 {
 				g := &gnUndirected{UndirectedBuilder: simple.NewUndirectedGraph()}
+				orig := g.NewNode()
+				g.AddNode(orig)
 				err := TunableClusteringScaleFree(g, n, m, p, nil)
 				if err != nil {
 					t.Fatalf("unexpected error: n=%d, m=%d, p=%v: %v", n, m, p, err)
 				}
+				if g.From(orig.ID()).Len() != 0 {
+					t.Errorf("edge added from already existing node: n=%d, m=%d, p=%v", n, m, p)
+				}
 				if g.addBackwards {
 					t.Errorf("edge added with From.ID > To.ID: n=%d, m=%d, p=%v", n, m, p)
 				}