diff --git a/render/container.go b/render/container.go
index 347d56745..5a20984ea 100644
--- a/render/container.go
+++ b/render/container.go
@@ -32,10 +32,7 @@ var ContainerRenderer = Memoise(MakeFilter(
 		return !ok || state != report.StateDeleted
 	},
 	MakeReduce(
-		MakeMap(
-			MapProcess2Container,
-			ProcessRenderer,
-		),
+		process2Container{},
 		ConnectionJoin(MapContainer2IP, report.Container),
 	),
 ))
@@ -219,39 +216,36 @@ func MapContainer2IP(m report.Node) []string {
 	return result
 }
 
-// MapProcess2Container maps process Nodes to container
-// Nodes.
+// process2Container maps process Nodes to container Nodes.
 //
-// Pseudo nodes are passed straight through.
-//
-// If this function is given a node without a docker_container_id, it
-// will produce an "Uncontained" pseudo node.
-//
-// Otherwise, this function will produce a node with the correct ID
+// This function will produce nodes with the correct ID
 // format for a container, but without any Major or Minor labels.
 // It does not have enough info to do that, and the resulting graph
 // must be merged with a container graph to get that info.
-func MapProcess2Container(n report.Node) report.Node {
-	// Propagate pseudo nodes
-	if n.Topology == Pseudo {
-		return n
-	}
 
-	// Otherwise, if the process is not in a container, group it into
-	// a per-host "Uncontained" node.
-	var (
-		id   string
-		node report.Node
-	)
-	if containerID, ok := n.Latest.Lookup(report.DockerContainerID); ok {
-		id = report.MakeContainerNodeID(containerID)
-		node = NewDerivedNode(id, n).WithTopology(report.Container)
-	} else {
-		hostID, _, _ := report.ParseProcessNodeID(n.ID)
-		id = MakePseudoNodeID(UncontainedID, hostID)
-		node = NewDerivedPseudoNode(id, n)
+type process2Container struct{}
+
+func (m process2Container) Render(ctx context.Context, rpt report.Report) Nodes {
+	processes := ProcessRenderer.Render(ctx, rpt)
+	ret := newJoinResults(nil)
+	for _, n := range processes.Nodes {
+		if n.Topology == Pseudo {
+			ret.passThrough(n)
+			continue
+		}
+
+		// If the process is not in a container, group it into
+		// a per-host "Uncontained" node.
+		if containerID, ok := n.Latest.Lookup(report.DockerContainerID); ok {
+			id := report.MakeContainerNodeID(containerID)
+			ret.addChildAndChildren(n, id, report.Container)
+		} else {
+			hostID, _, _ := report.ParseProcessNodeID(n.ID)
+			id := MakePseudoNodeID(UncontainedID, hostID)
+			ret.addChildAndChildren(n, id, Pseudo)
+		}
 	}
-	return node
+	return ret.result(processes)
 }
 
 // containerImageRenderer produces a graph where each node is a container image
diff --git a/render/container_test.go b/render/container_test.go
index 5bb3d1171..eeedc1b2c 100644
--- a/render/container_test.go
+++ b/render/container_test.go
@@ -2,7 +2,6 @@ package render_test
 
 import (
 	"context"
-	"fmt"
 	"testing"
 
 	"github.com/weaveworks/common/test"
@@ -25,32 +24,6 @@ var (
 	})
 )
 
-func TestMapProcess2Container(t *testing.T) {
-	for _, input := range []testcase{
-		{"empty", report.MakeNode("empty"), true},
-		{"basic process", report.MakeNodeWith("basic", map[string]string{report.PID: "201", report.DockerContainerID: "a1b2c3"}), true},
-		{"uncontained", report.MakeNodeWith("uncontained", map[string]string{report.PID: "201", report.HostNodeID: report.MakeHostNodeID("foo")}), true},
-	} {
-		testMap(t, render.MapProcess2Container, input)
-	}
-}
-
-type testcase struct {
-	name string
-	n    report.Node
-	ok   bool
-}
-
-func testMap(t *testing.T, f render.MapFunc, input testcase) {
-	if have := f(input.n); input.ok != (have.ID != "") {
-		name := input.name
-		if name == "" {
-			name = fmt.Sprintf("%v", input.n)
-		}
-		t.Errorf("%s: want %v, have %v", name, input.ok, have)
-	}
-}
-
 func TestContainerRenderer(t *testing.T) {
 	have := utils.Prune(render.ContainerWithImageNameRenderer.Render(context.Background(), fixture.Report).Nodes)
 	want := utils.Prune(expected.RenderedContainers)