diff --git a/cmd/root.go b/cmd/root.go
index 46d79070..173d4591 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -253,6 +253,10 @@ func addPersistentFlags() {
 	if err := viper.BindPFlag("allow-insecure-connections", RootCmd.PersistentFlags().Lookup("allow-insecure-connections")); err != nil {
 		panic(err)
 	}
+	RootCmd.PersistentFlags().Bool("custom-spec-support", false, "use dynamic SSZ decoding for non-mainnet presets such as Gnosis (slower; currently honoured only by 'validator exit')")
+	if err := viper.BindPFlag("custom-spec-support", RootCmd.PersistentFlags().Lookup("custom-spec-support")); err != nil {
+		panic(err)
+	}
 }
 
 // initConfig reads in config file and ENV variables if set.
diff --git a/cmd/validator/exit/command.go b/cmd/validator/exit/command.go
index b6a8d3ae..01fa159b 100644
--- a/cmd/validator/exit/command.go
+++ b/cmd/validator/exit/command.go
@@ -50,6 +50,7 @@ type command struct {
 	timeout                  time.Duration
 	connection               string
 	allowInsecureConnections bool
+	customSpecSupport        bool
 
 	// Information required to generate the operations.
 	chainInfo *beacon.ChainInfo
@@ -73,6 +74,7 @@ func newCommand(_ context.Context) (*command, error) {
 		timeout:                  viper.GetDuration("timeout"),
 		connection:               viper.GetString("connection"),
 		allowInsecureConnections: viper.GetBool("allow-insecure-connections"),
+		customSpecSupport:        viper.GetBool("custom-spec-support"),
 		prepareOffline:           viper.GetBool("prepare-offline"),
 		passphrases:              util.GetPassphrases(),
 		mnemonic:                 viper.GetString("mnemonic"),
diff --git a/cmd/validator/exit/process.go b/cmd/validator/exit/process.go
index c9bbc16e..e955e040 100644
--- a/cmd/validator/exit/process.go
+++ b/cmd/validator/exit/process.go
@@ -595,10 +595,11 @@ func (c *command) setup(ctx context.Context) error {
 	// Connect to the consensus node.
 	var err error
 	c.consensusClient, err = util.ConnectToBeaconNode(ctx, &util.ConnectOpts{
-		Address:       c.connection,
-		Timeout:       c.timeout,
-		AllowInsecure: c.allowInsecureConnections,
-		LogFallback:   !c.quiet,
+		Address:           c.connection,
+		Timeout:           c.timeout,
+		AllowInsecure:     c.allowInsecureConnections,
+		CustomSpecSupport: c.customSpecSupport,
+		LogFallback:       !c.quiet,
 	})
 	if err != nil {
 		return err
diff --git a/util/beaconnode.go b/util/beaconnode.go
index 54af7b64..01bc245d 100644
--- a/util/beaconnode.go
+++ b/util/beaconnode.go
@@ -37,11 +37,13 @@ var defaultBeaconNodeAddresses = []string{
 // fallbackBeaconNode is used if no other connection is supplied.
 var fallbackBeaconNode = "http://mainnet-consensus.attestant.io/"
 
+// ConnectOpts are the options for connecting to a beacon node.
 type ConnectOpts struct {
-	Address       string
-	Timeout       time.Duration
-	AllowInsecure bool
-	LogFallback   bool
+	Address           string
+	Timeout           time.Duration
+	AllowInsecure     bool
+	CustomSpecSupport bool
+	LogFallback       bool
 }
 
 // ConnectToBeaconNode connects to a beacon node at the given address.
@@ -56,12 +58,22 @@ func ConnectToBeaconNode(ctx context.Context, opts *ConnectOpts) (eth2client.Ser
 
 	if opts.Address != "" {
 		// We have an explicit address; use it.
-		return connectToBeaconNode(ctx, opts.Address, opts.Timeout, opts.AllowInsecure)
+		return connectToBeaconNode(ctx, &beaconNodeConnection{
+			address:           opts.Address,
+			timeout:           opts.Timeout,
+			allowInsecure:     opts.AllowInsecure,
+			customSpecSupport: opts.CustomSpecSupport,
+		})
 	}
 
 	// Try the defaults.
 	for _, address := range defaultBeaconNodeAddresses {
-		client, err := connectToBeaconNode(ctx, address, opts.Timeout, opts.AllowInsecure)
+		client, err := connectToBeaconNode(ctx, &beaconNodeConnection{
+			address:           address,
+			timeout:           opts.Timeout,
+			allowInsecure:     opts.AllowInsecure,
+			customSpecSupport: opts.CustomSpecSupport,
+		})
 		if err == nil {
 			return client, nil
 		}
@@ -71,7 +83,12 @@ func ConnectToBeaconNode(ctx context.Context, opts *ConnectOpts) (eth2client.Ser
 	if opts.LogFallback {
 		fmt.Fprintf(os.Stderr, "No connection supplied with --connection parameter and no local beacon node found, attempting to use mainnet fallback\n")
 	}
-	client, err := connectToBeaconNode(ctx, fallbackBeaconNode, opts.Timeout, true)
+	client, err := connectToBeaconNode(ctx, &beaconNodeConnection{
+		address:           fallbackBeaconNode,
+		timeout:           opts.Timeout,
+		allowInsecure:     true,
+		customSpecSupport: opts.CustomSpecSupport,
+	})
 	if err == nil {
 		return client, nil
 	}
@@ -79,11 +96,20 @@ func ConnectToBeaconNode(ctx context.Context, opts *ConnectOpts) (eth2client.Ser
 	return nil, errors.New("failed to connect to any beacon node")
 }
 
-func connectToBeaconNode(ctx context.Context, address string, timeout time.Duration, allowInsecure bool) (eth2client.Service, error) {
+// beaconNodeConnection holds the parameters for a single beacon node connection attempt.
+type beaconNodeConnection struct {
+	address           string
+	timeout           time.Duration
+	allowInsecure     bool
+	customSpecSupport bool
+}
+
+func connectToBeaconNode(ctx context.Context, conn *beaconNodeConnection) (eth2client.Service, error) {
+	address := conn.address
 	if !strings.HasPrefix(address, "http") {
 		address = fmt.Sprintf("http://%s", address)
 	}
-	if !allowInsecure {
+	if !conn.allowInsecure {
 		// Ensure the connection is either secure or local.
 		connectionURL, err := url.Parse(address)
 		if err != nil {
@@ -100,7 +126,8 @@ func connectToBeaconNode(ctx context.Context, address string, timeout time.Durat
 	eth2Client, err := http.New(ctx,
 		http.WithLogLevel(zerolog.Disabled),
 		http.WithAddress(address),
-		http.WithTimeout(timeout),
+		http.WithTimeout(conn.timeout),
+		http.WithCustomSpecSupport(conn.customSpecSupport),
 	)
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to connect to beacon node")