diff --git a/go/nix/bcacheup/bcacheup.go b/go/nix/bcacheup/bcacheup.go
index e44a3a6eb5..3f7777504a 100644
--- a/go/nix/bcacheup/bcacheup.go
+++ b/go/nix/bcacheup/bcacheup.go
@@ -32,6 +32,7 @@ import (
 var (
 	blobURLFlag              = flag.String("cache_url", "", "Cache URL")
 	stateSummaryIntervalFlag = flag.Duration("state_summary_interval", 10*time.Second, "Time between state summary outputs.")
+	deepCheckGalacticFlag    = flag.Bool("deep_check_galactic", false, "Ensure that all references are available in the cache before skipping, rather than just checking that the path itself is available.")
 )
 
 var (
@@ -159,7 +160,8 @@ type uploader struct {
 	storePath string
 	st        stateTracker
 
-	uploadSF singleflight.Group
+	uploadSF          singleflight.Group
+	deepCheckGalactic bool // if true, don't skip if this item is already present; always check the references to make sure they exist too.
 }
 
 type byteCounterWriter struct{ n uint64 }
@@ -314,15 +316,19 @@ func (u *uploader) uploadRefs(ctx context.Context, current string, refs []string
 func (u *uploader) upload(ctx context.Context, path string) error {
 	u.st.SetState(path, stateCheckingShouldUpload)
 
-	if ok, err := u.shouldUpload(ctx, path); err != nil {
+	shouldUploadThis, err := u.shouldUpload(ctx, path)
+	if err != nil {
 		u.st.SetState(path, stateFailed)
 		return fmt.Errorf("determining if we should upload %v: %w", path, err)
-	} else if !ok {
+	}
+	if !shouldUploadThis && !u.deepCheckGalactic {
 		u.st.SetState(path, stateSkipped)
 		return nil
 	}
 
-	log.Printf("Uploading %v", path)
+	if shouldUploadThis {
+		log.Printf("Uploading %v", path)
+	}
 
 	ni, err := u.store.NARInfo(path)
 	if err != nil {
@@ -336,6 +342,11 @@ func (u *uploader) upload(ctx context.Context, path string) error {
 		return fmt.Errorf("uploading references for %v: %w", path, err)
 	}
 
+	if !shouldUploadThis {
+		u.st.SetState(path, stateSkipped)
+		return nil
+	}
+
 	u.st.SetState(path, stateUploadingContent)
 	if !ni.NarHash.Valid() {
 		u.st.SetState(path, stateFailed)
@@ -427,9 +438,10 @@ func main() {
 	defer store.Close()
 
 	u := &uploader{
-		bucket:    bucket,
-		store:     store,
-		storePath: "/nix/store",
+		bucket:            bucket,
+		store:             store,
+		storePath:         "/nix/store",
+		deepCheckGalactic: *deepCheckGalacticFlag,
 	}
 
 	go func() {