diff --git a/api.go b/api.go
index 8d97c0e..43b9bb9 100644
--- a/api.go
+++ b/api.go
@@ -183,7 +183,7 @@ type ApiQueryRequest struct {
 	From        int64      `json:"from"`
 	To          int64      `json:"to"`
 	WithStats   bool       `json:"with-stats"`
-	WithUnit    bool       `json:"with-unit"`
+	WithUnit    bool       `json:"with-unit,omitempty"`
 	WithData    bool       `json:"with-data"`
 	WithPadding bool       `json:"with-padding"`
 	Queries     []ApiQuery `json:"queries"`
@@ -303,7 +303,7 @@ func handleQuery(rw http.ResponseWriter, r *http.Request) {
 			if req.WithPadding {
 				data.PadDataWithNull(req.From, req.To, query.Metric)
 			}
-			if req.WithUnit {
+			if req.WithUnit && len(unit) > 0 {
 				data.Unit = unit
 			}
 			if !req.WithData {
diff --git a/archive.go b/archive.go
index c7d84e9..ac95104 100644
--- a/archive.go
+++ b/archive.go
@@ -24,7 +24,7 @@ import (
 type CheckpointMetrics struct {
 	Frequency int64   `json:"frequency"`
 	Start     int64   `json:"start"`
-	Unit      string  `json:"unit"`
+	Unit      string  `json:"unit,omitempty"`
 	Data      []Float `json:"data"`
 }
 
@@ -312,7 +312,7 @@ func (l *level) loadFile(cf *CheckpointFile, m *MemoryStore) error {
 			frequency: metric.Frequency,
 			start:     metric.Start,
 			data:      metric.Data[0:n:n], // Space is wasted here :(
-			unit:      "",
+			unit:      metric.Unit,
 			prev:      nil,
 			next:      nil,
 			archived:  true,
diff --git a/debug.go b/debug.go
index 88af59f..567943d 100644
--- a/debug.go
+++ b/debug.go
@@ -21,6 +21,9 @@ func (b *buffer) debugDump(buf []byte) []byte {
 	if b.archived {
 		buf = append(buf, `,"saved":true`...)
 	}
+	if b.unit != "" {
+		buf = append(buf, fmt.Sprintf(`,"unit":"%s"`, b.unit)...)
+	}
 	if b.next != nil {
 		buf = append(buf, `},`...)
 	} else {