diff --git a/api.go b/api.go
index a5c6f4202..3a94e7918 100644
--- a/api.go
+++ b/api.go
@@ -32,6 +32,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"syscall"
 	"time"
 
 	"github.com/pilosa/pilosa/v2/disco"
@@ -919,10 +920,11 @@ type IndexUsage struct {
 
 // FieldUsage represents the storage space used on disk by one field, on one node
 type FieldUsage struct {
-	Total     uint64 `json:"total"`
-	Fragments uint64 `json:"fragments"`
-	Keys      uint64 `json:"keys"`
-	Metadata  uint64 `json:"metadata"`
+	Total      uint64 `json:"total"`
+	Fragments  uint64 `json:"fragments"`
+	Keys       uint64 `json:"keys"`
+	Metadata   uint64 `json:"metadata"`
+	ChangeTime syscall.Timespec
 }
 
 // MemoryUsage represents the memory used by one node.
@@ -936,9 +938,17 @@ func (api *API) Usage(ctx context.Context, remote bool) (map[string]NodeUsage, e
 	span, _ := tracing.StartSpanFromContext(ctx, "API.Usage")
 	defer span.Finish()
 
+	//initialize cache
 	if api.usageCache == nil {
 		api.usageCache = make(map[string]NodeUsage)
 	}
+	if api.usageCache[api.server.nodeID].Disk.IndexUsage == nil {
+		api.usageCache[api.server.nodeID] = NodeUsage{
+			Disk: DiskUsage{
+				IndexUsage: make(map[string]IndexUsage),
+			},
+		}
+	}
 
 	indexDetails, nodeMetadataBytes, err := api.holder.Txf().IndexUsageDetails(api.usageCache[api.server.nodeID].Disk.IndexUsage)
 	if err != nil {
@@ -977,7 +987,7 @@ func (api *API) Usage(ctx context.Context, remote bool) (map[string]NodeUsage, e
 			TotalUse: memoryUse,
 		},
 	}
-	nodeUsages[api.server.nodeID] = nodeUsage
+	api.usageCache[api.server.nodeID] = nodeUsage
 
 	// Collect usage from remote nodes
 	if !remote {
@@ -990,10 +1000,10 @@ func (api *API) Usage(ctx context.Context, remote bool) (map[string]NodeUsage, e
 			if err != nil {
 				return nil, errors.Wrapf(err, "collecting disk usage from %s", node.URI)
 			}
-			nodeUsages[node.ID] = nodeUsage[node.ID]
+			api.usageCache[node.ID] = nodeUsage[node.ID]
 		}
 	}
-	return nodeUsages, nil
+	return api.usageCache, nil
 }
 
 // RecalculateCaches forces all TopN caches to be updated.
diff --git a/txfactory.go b/txfactory.go
index 1c04023a4..ce4581f58 100644
--- a/txfactory.go
+++ b/txfactory.go
@@ -599,18 +599,15 @@ func (f *TxFactory) IndexUsageDetails(indexUsage map[string]IndexUsage) (map[str
 		flds := idx.Fields()
 		for _, fld := range flds {
 			field := fld.Name()
-			_, found := indexUsage[index].Fields[field]
-			var valid bool
-			if found {
-				fieldPath := path.Join(indexPath, FieldsDir, field)
-				fstat, err := os.Stat(fieldPath)
-				if err != nil {
-					return indexUsage, 0, errors.Wrap(err, "getting field path")
-				}
-				valid = indexUsage[index].Fields[field].ChangeTime == fstat.Sys().(*syscall.Stat_t).Ctimespec
-
+			fieldPath := path.Join(indexPath, FieldsDir, field)
+			fstat, err := os.Stat(fieldPath)
+			if err != nil {
+				return indexUsage, 0, errors.Wrap(err, "getting field path")
 			}
-			if !found || !valid {
+			changeTime := fstat.Sys().(*syscall.Stat_t).Ctimespec
+			_, found := indexUsage[index].Fields[field]
+
+			if !found || (indexUsage[index].Fields[field].ChangeTime != changeTime) {
 				if field == "_keys" {
 					continue
 				}
@@ -644,6 +641,7 @@ func (f *TxFactory) IndexUsageDetails(indexUsage map[string]IndexUsage) (map[str
 				// add non-roaring to roaring
 				fUsage.Fragments += fragmentUsage
 				fUsage.Total += fragmentUsage
+				fUsage.ChangeTime = changeTime
 
 				indexUsage[index].Fields[field] = fUsage
 			}