diff --git a/catalyst-uploader.go b/catalyst-uploader.go
index d6cf3b0..9bfc65b 100644
--- a/catalyst-uploader.go
+++ b/catalyst-uploader.go
@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"net/url"
 	"os"
+	"strings"
 	"time"
 
 	"github.com/golang/glog"
@@ -37,7 +38,7 @@ func run() int {
 	describe := fs.Bool("j", false, "Describe supported storage services in JSON format and exit")
 	verbosity := fs.String("v", "", "Log verbosity.  {4|5|6}")
 	timeout := fs.Duration("t", 30*time.Second, "Upload timeout")
-	storageBackupURLs := jsonFlag[core.StorageBackupURLs](fs, "storage-backup-urls", `JSON array of {"primary":X,"backup":Y} objects with base storage URLs. If a file fails uploading to one of the primary storages (detected by prefix), it will fallback to the corresponding backup URL after having the prefix replaced`)
+	storageBackupURLs := CommaMapFlag(fs, "storage-backup-urls", `Comma-separated map of primary to backup storage URLs. If a file fails uploading to one of the primary storages (detected by prefix), it will fallback to the corresponding backup URL after having the prefix replaced`)
 
 	_ = fs.String("config", "", "config file (optional)")
 
@@ -94,7 +95,7 @@ func run() int {
 		return 1
 	}
 
-	out, err := core.Upload(os.Stdin, uri, WaitBetweenWrites, *timeout, storageBackupURLs)
+	out, err := core.Upload(os.Stdin, uri, WaitBetweenWrites, *timeout, *storageBackupURLs)
 	if err != nil {
 		glog.Errorf("Uploader failed for %s: %s", uri.Redacted(), err)
 		return 1
@@ -117,10 +118,29 @@ func run() int {
 	return 0
 }
 
-func jsonFlag[T any](fs *flag.FlagSet, name string, usage string) T {
-	var value T
+// handles -foo=key1=value1,key2=value2
+func CommaMapFlag(fs *flag.FlagSet, name string, usage string) *map[string]string {
+	var dest map[string]string
 	fs.Func(name, usage, func(s string) error {
-		return json.Unmarshal([]byte(s), &value)
+		var err error
+		dest, err = parseCommaMap(s)
+		return err
 	})
-	return value
+	return &dest
+}
+
+func parseCommaMap(s string) (map[string]string, error) {
+	output := map[string]string{}
+	if s == "" {
+		return output, nil
+	}
+	for _, pair := range strings.Split(s, ",") {
+		kv := strings.Split(pair, "=")
+		if len(kv) != 2 {
+			return map[string]string{}, fmt.Errorf("failed to parse keypairs, -option=k1=v1,k2=v2 format required, got %s", s)
+		}
+		k, v := kv[0], kv[1]
+		output[k] = v
+	}
+	return output, nil
 }
diff --git a/core/uploader.go b/core/uploader.go
index f80cbf0..b148752 100644
--- a/core/uploader.go
+++ b/core/uploader.go
@@ -46,12 +46,7 @@ var expiryField = map[string]string{
 	"Object-Expires": "+168h", // Objects will be deleted after 7 days
 }
 
-type StorageBackupURLs []struct {
-	Primary string `json:"primary"`
-	Backup  string `json:"backup"`
-}
-
-func Upload(input io.Reader, outputURI *url.URL, waitBetweenWrites, writeTimeout time.Duration, storageBackupURLs StorageBackupURLs) (*drivers.SaveDataOutput, error) {
+func Upload(input io.Reader, outputURI *url.URL, waitBetweenWrites, writeTimeout time.Duration, storageBackupURLs map[string]string) (*drivers.SaveDataOutput, error) {
 	if strings.HasSuffix(outputURI.Path, ".ts") || strings.HasSuffix(outputURI.Path, ".mp4") {
 		// For segments we just write them in one go here and return early.
 		// (Otherwise the incremental write logic below caused issues with clipping since it results in partial segments being written.)
@@ -118,7 +113,7 @@ func Upload(input io.Reader, outputURI *url.URL, waitBetweenWrites, writeTimeout
 	return nil, nil
 }
 
-func uploadFileWithBackup(outputURI *url.URL, fileContents []byte, fields *drivers.FileProperties, writeTimeout time.Duration, withRetries bool, storageBackupURLs StorageBackupURLs) (out *drivers.SaveDataOutput, bytesWritten int64, err error) {
+func uploadFileWithBackup(outputURI *url.URL, fileContents []byte, fields *drivers.FileProperties, writeTimeout time.Duration, withRetries bool, storageBackupURLs map[string]string) (out *drivers.SaveDataOutput, bytesWritten int64, err error) {
 	out, bytesWritten, primaryErr := uploadFile(outputURI, fileContents, fields, writeTimeout, withRetries)
 	if primaryErr == nil {
 		return out, bytesWritten, nil
@@ -134,11 +129,11 @@ func uploadFileWithBackup(outputURI *url.URL, fileContents []byte, fields *drive
 	return uploadFile(backupURI, fileContents, fields, writeTimeout, withRetries)
 }
 
-func buildBackupURI(outputURI *url.URL, storageBackupURLs StorageBackupURLs) (*url.URL, error) {
+func buildBackupURI(outputURI *url.URL, storageBackupURLs map[string]string) (*url.URL, error) {
 	outputURIStr := outputURI.String()
-	for _, strj := range storageBackupURLs {
-		if strings.HasPrefix(outputURIStr, strj.Primary) {
-			backupStr := strings.Replace(outputURIStr, strj.Primary, strj.Backup, 1)
+	for primary, backup := range storageBackupURLs {
+		if strings.HasPrefix(outputURIStr, primary) {
+			backupStr := strings.Replace(outputURIStr, primary, backup, 1)
 			return url.Parse(backupStr)
 		}
 	}
@@ -185,7 +180,7 @@ func uploadFile(outputURI *url.URL, fileContents []byte, fields *drivers.FilePro
 	return out, bytesWritten, err
 }
 
-func extractThumb(outputURI *url.URL, segment []byte, storageBackupURLs StorageBackupURLs) error {
+func extractThumb(outputURI *url.URL, segment []byte, storageBackupURLs map[string]string) error {
 	tmpDir, err := os.MkdirTemp(os.TempDir(), "thumb-*")
 	if err != nil {
 		return fmt.Errorf("temp file creation failed: %w", err)