diff --git a/GUIDE.md b/GUIDE.md
index 040c9e2..23170f6 100644
--- a/GUIDE.md
+++ b/GUIDE.md
@@ -41,15 +41,15 @@ type RouterClient interface {
 		NewLeaseDuration uint32,
 	) (err error)
 
-    GetExternalIPAddress() (
-        NewExternalIPAddress string,
-        err error,
-    )
+	GetExternalIPAddress() (
+		NewExternalIPAddress string,
+		err error,
+	)
 }
 
 func PickRouterClient(ctx context.Context) (RouterClient, error) {
 	tasks, _ := errgroup.WithContext(ctx)
-    // Request each type of client in parallel, and return what is found.
+	// Request each type of client in parallel, and return what is found.
 	var ip1Clients []*internetgateway2.WANIPConnection1
 	tasks.Go(func() error {
 		var err error
@@ -73,9 +73,9 @@ func PickRouterClient(ctx context.Context) (RouterClient, error) {
 		return nil, err
 	}
 
-    // Trivial handling for where we find exactly one device to talk to, you
-    // might want to provide more flexible handling than this if multiple
-    // devices are found.
+	// Trivial handling for where we find exactly one device to talk to, you
+	// might want to provide more flexible handling than this if multiple
+	// devices are found.
 	switch {
 	case len(ip2Clients) == 1:
 		return ip2Clients[0], nil
@@ -94,36 +94,36 @@ external IP address and forward it to a port on your local network, e.g:
 
 ```go
 func GetIPAndForwardPort(ctx context.Context) error {
-    client, err := PickRouterClient(ctx)
-    if err != nil {
-        return err
-    }
-
-    externalIP, err := client.GetExternalIPAddress()
-    if err != nil {
-        return err
-    }
-    fmt.Println("Our external IP address is: ", externalIP)
-
-    return client.AddPortMapping(
+	client, err := PickRouterClient(ctx)
+	if err != nil {
+		return err
+	}
+
+	externalIP, err := client.GetExternalIPAddress()
+	if err != nil {
+		return err
+	}
+	fmt.Println("Our external IP address is: ", externalIP)
+
+	return client.AddPortMapping(
 		"",
-        // External port number to expose to Internet:
+		// External port number to expose to Internet:
 		1234,
-        // Forward TCP (this could be "UDP" if we wanted that instead).
+		// Forward TCP (this could be "UDP" if we wanted that instead).
 		"TCP",
-        // Internal port number on the LAN to forward to.
-        // Some routers might not support this being different to the external
-        // port number.
+		// Internal port number on the LAN to forward to.
+		// Some routers might not support this being different to the external
+		// port number.
 		1234,
-        // Internal address on the LAN we want to forward to.
+		// Internal address on the LAN we want to forward to.
 		"192.168.1.6",
-        // Enabled:
+		// Enabled:
 		true,
-        // Informational description for the client requesting the port forwarding.
+		// Informational description for the client requesting the port forwarding.
 		"MyProgramName",
-        // How long should the port forward last for in seconds.
-        // If you want to keep it open for longer and potentially across router
-        // resets, you might want to periodically request before this elapses.
+		// How long should the port forward last for in seconds.
+		// If you want to keep it open for longer and potentially across router
+		// resets, you might want to periodically request before this elapses.
 		3600,
 	)
 }