diff --git a/docs/notifications.md b/docs/notifications.md
index 7921e19..a69b00b 100644
--- a/docs/notifications.md
+++ b/docs/notifications.md
@@ -181,7 +181,8 @@ If you want to disable TLS verification for the Gotify instance, you can use eit
 
 To send notifications via shoutrrr, the following command-line options, or their corresponding environment variables, can be set:
 
--   `--notification-url` (env. `WATCHTOWER_NOTIFICATION_URL`): The shoutrrr service URL to be used.
+-   `--notification-url` (env. `WATCHTOWER_NOTIFICATION_URL`): The shoutrrr service URL to be used.  This option can also reference a file, in which case the contents of the file are used.
+
 
 Go to [containrrr.dev/shoutrrr/v0.6/services/overview](https://containrrr.dev/shoutrrr/v0.6/services/overview) to
 learn more about the different service URLs you can use. You can define multiple services by space separating the
diff --git a/internal/flags/flags.go b/internal/flags/flags.go
index 2af8678..531d5d2 100644
--- a/internal/flags/flags.go
+++ b/internal/flags/flags.go
@@ -1,6 +1,7 @@
 package flags
 
 import (
+	"bufio"
 	"errors"
 	"io/ioutil"
 	"os"
@@ -444,6 +445,7 @@ func GetSecretsFromFiles(rootCmd *cobra.Command) {
 		"notification-slack-hook-url",
 		"notification-msteams-hook",
 		"notification-gotify-token",
+		"notification-url",
 	}
 	for _, secret := range secrets {
 		getSecretFromFile(flags, secret)
@@ -452,10 +454,33 @@ func GetSecretsFromFiles(rootCmd *cobra.Command) {
 
 // getSecretFromFile will check if the flag contains a reference to a file; if it does, replaces the value of the flag with the contents of the file.
 func getSecretFromFile(flags *pflag.FlagSet, secret string) {
-	value, err := flags.GetString(secret)
-	if err != nil {
-		log.Error(err)
+	flag := flags.Lookup(secret)
+	if sliceValue, ok := flag.Value.(pflag.SliceValue); ok {
+		oldValues := sliceValue.GetSlice()
+		values := make([]string, 0, len(oldValues))
+		for _, value := range oldValues {
+			if value != "" && isFile(value) {
+				file, err := os.Open(value)
+				if err != nil {
+					log.Fatal(err)
+				}
+				scanner := bufio.NewScanner(file)
+				for scanner.Scan() {
+					line := scanner.Text()
+					if line == "" {
+						continue
+					}
+					values = append(values, line)
+				}
+			} else {
+				values = append(values, value)
+			}
+		}
+		sliceValue.Replace(values)
+		return
 	}
+
+	value := flag.Value.String()
 	if value != "" && isFile(value) {
 		file, err := ioutil.ReadFile(value)
 		if err != nil {
diff --git a/internal/flags/flags_test.go b/internal/flags/flags_test.go
index 1a904dd..7d3c55e 100644
--- a/internal/flags/flags_test.go
+++ b/internal/flags/flags_test.go
@@ -50,6 +50,7 @@ func TestGetSecretsFromFilesWithString(t *testing.T) {
 
 	err := os.Setenv("WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PASSWORD", value)
 	require.NoError(t, err)
+	defer os.Unsetenv("WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PASSWORD")
 
 	testGetSecretsFromFiles(t, "notification-email-server-password", value)
 }
@@ -69,17 +70,40 @@ func TestGetSecretsFromFilesWithFile(t *testing.T) {
 
 	err = os.Setenv("WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PASSWORD", file.Name())
 	require.NoError(t, err)
+	defer os.Unsetenv("WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PASSWORD")
 
 	testGetSecretsFromFiles(t, "notification-email-server-password", value)
 }
 
-func testGetSecretsFromFiles(t *testing.T, flagName string, expected string) {
+func TestGetSliceSecretsFromFiles(t *testing.T) {
+	values := []string{"entry2", "", "entry3"}
+
+	// Create the temporary file which will contain a secret.
+	file, err := ioutil.TempFile(os.TempDir(), "watchtower-")
+	require.NoError(t, err)
+	defer os.Remove(file.Name()) // Make sure to remove the temporary file later.
+
+	// Write the secret to the temporary file.
+	for _, value := range values {
+		_, err = file.WriteString("\n" + value)
+		require.NoError(t, err)
+	}
+	file.Close()
+
+	testGetSecretsFromFiles(t, "notification-url", `[entry1,entry2,entry3]`,
+		`--notification-url`, "entry1",
+		`--notification-url`, file.Name())
+}
+
+func testGetSecretsFromFiles(t *testing.T, flagName string, expected string, args ...string) {
 	cmd := new(cobra.Command)
 	SetDefaults()
 	RegisterNotificationFlags(cmd)
+	require.NoError(t, cmd.ParseFlags(args))
 	GetSecretsFromFiles(cmd)
-	value, err := cmd.PersistentFlags().GetString(flagName)
-	require.NoError(t, err)
+	flag := cmd.PersistentFlags().Lookup(flagName)
+	require.NotNil(t, flag)
+	value := flag.Value.String()
 
 	assert.Equal(t, expected, value)
 }