diff --git a/.gitignore b/.gitignore
index 13af037bf..25e84215a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -56,4 +56,4 @@ experimental/_integration/_integration
 app/static.go
 prog/static.go
 vendor/github.com/2opremio/go-1/codec/codecgen/codecgen
-report/report.codecgen.go
\ No newline at end of file
+*.codecgen.go
diff --git a/Makefile b/Makefile
index 973448a18..7bbf2c1c8 100644
--- a/Makefile
+++ b/Makefile
@@ -17,6 +17,7 @@ DOCKER_DISTRIB_URL=https://get.docker.com/builds/Linux/x86_64/docker-$(DOCKER_VE
 RUNSVINIT=vendor/runsvinit/runsvinit
 CODECGEN_DIR=vendor/github.com/2opremio/go-1/codec/codecgen
 CODECGEN_EXE=$(CODECGEN_DIR)/codecgen
+CODECGEN_TARGETS=report/report.codecgen.go render/render.codecgen.go render/detailed/detailed.codecgen.go
 RM=--rm
 RUN_FLAGS=-ti
 BUILD_IN_CONTAINER=true
@@ -60,7 +61,7 @@ $(SCOPE_EXE) $(RUNSVINIT) lint tests shell: $(SCOPE_BACKEND_BUILD_UPTODATE)
 
 else
 
-$(SCOPE_EXE): $(SCOPE_BACKEND_BUILD_UPTODATE)
+$(SCOPE_EXE): $(SCOPE_BACKEND_BUILD_UPTODATE) $(CODECGEN_TARGETS)
 	time $(GO) build $(GO_BUILD_FLAGS) -o $@ ./$(@D)
 	@strings $@ | grep cgo_stub\\\.go >/dev/null || { \
 	        rm $@; \
@@ -71,11 +72,10 @@ $(SCOPE_EXE): $(SCOPE_BACKEND_BUILD_UPTODATE)
 	        false; \
 	    }
 
-$(SCOPE_EXE): report/report.codecgen.go
-
-CODECGEN_REPORT_SOURCES=$(shell find report/ -type f -name '*.go' -not -name '*_test.go' -not -name '*.codecgen.go' -not -name '*.generated.go')
-report/report.codecgen.go: $(CODECGEN_EXE) $(CODECGEN_REPORT_SOURCES)
-	cd report && $(GO_HOST_ENV) ../$(CODECGEN_EXE) -u -o $(@F) $(notdir $(CODECGEN_REPORT_SOURCES))
+# Enable second  expansion to automatically generate the dependencies of codecgen
+.SECONDEXPANSION:
+%.codecgen.go: $(CODECGEN_EXE) $$(shell find $$(@D) -maxdepth 1 -type f -name '*.go' -not -name '*_test.go' -not -name '*.codecgen.go' -not -name '*.generated.go')
+	cd $(@D) && $(GO_HOST_ENV) $(shell pwd)/$(CODECGEN_EXE) -u -o $(@F) $(notdir $(filter-out $<,$^))
 
 $(CODECGEN_EXE): $(CODECGEN_DIR)/*.go
 	$(GO_HOST_ENV) $(GO) build $(GO_BUILD_TAGS) -o $@ ./$(@D)
@@ -137,7 +137,8 @@ clean:
 	$(GO) clean ./...
 	$(SUDO) docker rmi $(SCOPE_UI_BUILD_IMAGE) $(SCOPE_BACKEND_BUILD_IMAGE) >/dev/null 2>&1 || true
 	rm -rf $(SCOPE_EXPORT) $(SCOPE_UI_BUILD_UPTODATE) $(SCOPE_BACKEND_BUILD_UPTODATE) \
-		$(SCOPE_EXE) $(RUNSVINIT) prog/static.go client/build/app.js docker/weave .pkg
+		$(SCOPE_EXE) $(RUNSVINIT) prog/static.go client/build/app.js docker/weave .pkg \
+		$(CODECGEN_TARGETS) $(CODECGEN_EXE)
 
 deps:
 	$(GO) get -u -f $(GO_BUILD_TAGS) \
diff --git a/render/detailed/metadata.go b/render/detailed/metadata.go
index 124823eae..2cebac534 100644
--- a/render/detailed/metadata.go
+++ b/render/detailed/metadata.go
@@ -1,7 +1,6 @@
 package detailed
 
 import (
-	"bytes"
 	"strconv"
 	"strings"
 
@@ -105,6 +104,7 @@ func (c Counter) MetadataRows(n report.Node) []MetadataRow {
 }
 
 // MetadataRow is a row for the metadata table.
+// codecgen: skip
 type MetadataRow struct {
 	ID    string
 	Value string
@@ -119,23 +119,44 @@ func (m MetadataRow) Copy() MetadataRow {
 	}
 }
 
-// MarshalJSON marshals this MetadataRow to json. It adds a label before
+// MarshalJSON shouldn't be used, use CodecEncodeSelf instead
+func (MetadataRow) MarshalJSON() ([]byte, error) {
+	panic("MarshalJSON shouldn't be used, use CodecEncodeSelf instead")
+}
+
+// UnmarshalJSON shouldn't be used, use CodecDecodeSelf instead
+func (*MetadataRow) UnmarshalJSON(b []byte) error {
+	panic("UnmarshalJSON shouldn't be used, use CodecDecodeSelf instead")
+}
+
+type labelledMetadataRow struct {
+	ID    string `json:"id"`
+	Label string `json:"label"`
+	Value string `json:"value"`
+	Prime bool   `json:"prime,omitempty"`
+}
+
+// CodecEncodeSelf marshals this MetadataRow. It adds a label before
 // rendering.
-func (m MetadataRow) MarshalJSON() ([]byte, error) {
-	buf := bytes.Buffer{}
-	encoder := codec.NewEncoder(&buf, &codec.JsonHandle{})
-	err := encoder.Encode(struct {
-		ID    string `json:"id"`
-		Label string `json:"label"`
-		Value string `json:"value"`
-		Prime bool   `json:"prime,omitempty"`
-	}{
+func (m *MetadataRow) CodecEncodeSelf(encoder *codec.Encoder) {
+	in := labelledMetadataRow{
 		ID:    m.ID,
 		Label: Label(m.ID),
 		Value: m.Value,
 		Prime: m.Prime,
-	})
-	return buf.Bytes(), err
+	}
+	encoder.Encode(in)
+}
+
+// CodecDecodeSelf implements codec.Selfer
+func (m *MetadataRow) CodecDecodeSelf(decoder *codec.Decoder) {
+	var in labelledMetadataRow
+	decoder.Decode(&in)
+	*m = MetadataRow{
+		ID:    in.ID,
+		Value: in.Value,
+		Prime: in.Prime,
+	}
 }
 
 // NodeMetadata produces a table (to be consumed directly by the UI) based on
diff --git a/render/detailed/metrics.go b/render/detailed/metrics.go
index 182c47ffc..18751a249 100644
--- a/render/detailed/metrics.go
+++ b/render/detailed/metrics.go
@@ -1,7 +1,6 @@
 package detailed
 
 import (
-	"bytes"
 	"math"
 
 	"github.com/ugorji/go/codec"
@@ -37,6 +36,7 @@ var (
 
 // MetricRow is a tuple of data used to render a metric as a sparkline and
 // accoutrements.
+// codecgen: skip
 type MetricRow struct {
 	ID     string
 	Format string
@@ -60,19 +60,29 @@ func (m MetricRow) Copy() MetricRow {
 	return row
 }
 
-// MarshalJSON marshals this MetricRow to json. It takes the basic Metric
+// MarshalJSON shouldn't be used, use CodecEncodeSelf instead
+func (MetricRow) MarshalJSON() ([]byte, error) {
+	panic("MarshalJSON shouldn't be used, use CodecEncodeSelf instead")
+}
+
+// UnmarshalJSON shouldn't be used, use CodecDecodeSelf instead
+func (*MetricRow) UnmarshalJSON(b []byte) error {
+	panic("UnmarshalJSON shouldn't be used, use CodecDecodeSelf instead")
+}
+
+type wiredMetricRow struct {
+	ID     string  `json:"id"`
+	Label  string  `json:"label"`
+	Format string  `json:"format,omitempty"`
+	Group  string  `json:"group,omitempty"`
+	Value  float64 `json:"value"`
+	report.WireMetrics
+}
+
+// CodecEncodeSelf marshals this MetricRow. It takes the basic Metric
 // rendering, then adds some row-specific fields.
-func (m MetricRow) MarshalJSON() ([]byte, error) {
-	buf := bytes.Buffer{}
-	encoder := codec.NewEncoder(&buf, &codec.JsonHandle{})
-	err := encoder.Encode(struct {
-		ID     string  `json:"id"`
-		Label  string  `json:"label"`
-		Format string  `json:"format,omitempty"`
-		Group  string  `json:"group,omitempty"`
-		Value  float64 `json:"value"`
-		report.WireMetrics
-	}{
+func (m *MetricRow) CodecEncodeSelf(encoder *codec.Encoder) {
+	encoder.Encode(wiredMetricRow{
 		ID:          m.ID,
 		Label:       Label(m.ID),
 		Format:      m.Format,
@@ -80,7 +90,21 @@ func (m MetricRow) MarshalJSON() ([]byte, error) {
 		Value:       m.Value,
 		WireMetrics: m.Metric.ToIntermediate(),
 	})
-	return buf.Bytes(), err
+}
+
+// CodecDecodeSelf implements codec.Selfer
+func (m *MetricRow) CodecDecodeSelf(decoder *codec.Decoder) {
+	var in wiredMetricRow
+	decoder.Decode(&in)
+
+	metric := in.WireMetrics.FromIntermediate()
+	*m = MetricRow{
+		ID:     in.ID,
+		Format: in.Format,
+		Group:  in.Group,
+		Value:  in.Value,
+		Metric: &metric,
+	}
 }
 
 // NodeMetrics produces a table (to be consumed directly by the UI) based on
diff --git a/render/detailed/summary.go b/render/detailed/summary.go
index 8cc65c054..14e252c08 100644
--- a/render/detailed/summary.go
+++ b/render/detailed/summary.go
@@ -36,6 +36,7 @@ func (g NodeSummaryGroup) Copy() NodeSummaryGroup {
 
 // Column provides special json serialization for column ids, so they include
 // their label for the frontend.
+// codecgen: skip
 type Column string
 
 // CodecEncodeSelf implements codec.Selfer
diff --git a/report/controls.go b/report/controls.go
index d6cb702a7..90aa4363e 100644
--- a/report/controls.go
+++ b/report/controls.go
@@ -4,6 +4,7 @@ import (
 	"time"
 
 	"github.com/ugorji/go/codec"
+
 	"github.com/weaveworks/scope/common/mtime"
 )
 
diff --git a/report/metrics.go b/report/metrics.go
index bd355e89c..182ef0337 100644
--- a/report/metrics.go
+++ b/report/metrics.go
@@ -254,7 +254,9 @@ func (m Metric) ToIntermediate() WireMetrics {
 	}
 }
 
-func (m WireMetrics) fromIntermediate() Metric {
+// FromIntermediate obtains the metric from a representation suitable
+// for serialization.
+func (m WireMetrics) FromIntermediate() Metric {
 	samples := ps.NewList()
 	for _, s := range m.Samples {
 		samples = samples.Cons(s)
@@ -280,7 +282,7 @@ func (m *Metric) CodecDecodeSelf(decoder *codec.Decoder) {
 	if err := decoder.Decode(&in); err != nil {
 		return
 	}
-	*m = in.fromIntermediate()
+	*m = in.FromIntermediate()
 }
 
 // MarshalJSON shouldn't be used, use CodecEncodeSelf instead
@@ -306,6 +308,6 @@ func (m *Metric) GobDecode(input []byte) error {
 	if err := gob.NewDecoder(bytes.NewBuffer(input)).Decode(&in); err != nil {
 		return err
 	}
-	*m = in.fromIntermediate()
+	*m = in.FromIntermediate()
 	return nil
 }