diff --git a/cmd/yggdrasil/main.go b/cmd/yggdrasil/main.go
index cc54d3d..c3add0c 100644
--- a/cmd/yggdrasil/main.go
+++ b/cmd/yggdrasil/main.go
@@ -9,7 +9,6 @@ import (
 	"log"
 	"os"
 	"os/signal"
-	"regexp"
 	"strings"
 	"syscall"
 
@@ -221,15 +220,6 @@ func main() {
 	// Setup the Yggdrasil node itself. The node{} type includes a Core, so we
 	// don't need to create this manually.
 	n := node{}
-	// Check to see if any multicast interface expressions were provided in the
-	// config. If they were then set them now.
-	for _, ll := range cfg.MulticastInterfaces {
-		ifceExpr, err := regexp.Compile(ll)
-		if err != nil {
-			panic(err)
-		}
-		n.core.AddMulticastInterfaceExpr(ifceExpr)
-	}
 	// Now that we have a working configuration, we can now actually start
 	// Yggdrasil. This will start the router, switch, DHT node, TCP and UDP
 	// sockets, TUN/TAP adapter and multicast discovery port.
diff --git a/src/yggdrasil/core.go b/src/yggdrasil/core.go
index dc1b8f0..3382562 100644
--- a/src/yggdrasil/core.go
+++ b/src/yggdrasil/core.go
@@ -5,7 +5,6 @@ import (
 	"io/ioutil"
 	"log"
 	"net"
-	"regexp"
 	"sync"
 	"time"
 
@@ -47,7 +46,6 @@ type Core struct {
 	tcp         tcpInterface
 	awdl        awdl
 	log         *log.Logger
-	ifceExpr    []*regexp.Regexp // the zone of link-local IPv6 peers must match this
 }
 
 func (c *Core) init() error {
@@ -313,13 +311,6 @@ func (c *Core) AddPeer(addr string, sintf string) error {
 	return c.admin.addPeer(addr, sintf)
 }
 
-// Adds an expression to select multicast interfaces for peer discovery. This
-// should be done before calling Start. This function can be called multiple
-// times to add multiple search expressions.
-func (c *Core) AddMulticastInterfaceExpr(expr *regexp.Regexp) {
-	c.ifceExpr = append(c.ifceExpr, expr)
-}
-
 // Adds an allowed public key. This allow peerings to be restricted only to
 // keys that you have selected.
 func (c *Core) AddAllowedEncryptionPublicKey(boxStr string) error {
diff --git a/src/yggdrasil/multicast.go b/src/yggdrasil/multicast.go
index cf84fed..4087895 100644
--- a/src/yggdrasil/multicast.go
+++ b/src/yggdrasil/multicast.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"net"
+	"regexp"
 	"sync"
 	"time"
 
@@ -35,15 +36,13 @@ func (m *multicast) init(core *Core) {
 	}()
 	m.groupAddr = "[ff02::114]:9001"
 	// Check if we've been given any expressions
-	if len(m.core.ifceExpr) == 0 {
-		return
+	if count := len(m.interfaces()); count != 0 {
+		m.core.log.Println("Found", count, "multicast interface(s)")
 	}
-	// Ask the system for network interfaces
-	m.core.log.Println("Found", len(m.interfaces()), "multicast interface(s)")
 }
 
 func (m *multicast) start() error {
-	if len(m.core.ifceExpr) == 0 {
+	if len(m.interfaces()) == 0 {
 		m.core.log.Println("Multicast discovery is disabled")
 	} else {
 		m.core.log.Println("Multicast discovery is enabled")
@@ -71,6 +70,10 @@ func (m *multicast) start() error {
 }
 
 func (m *multicast) interfaces() []net.Interface {
+	// Get interface expressions from config
+	m.core.configMutex.RLock()
+	exprs := m.core.config.MulticastInterfaces
+	m.core.configMutex.RUnlock()
 	// Ask the system for network interfaces
 	var interfaces []net.Interface
 	allifaces, err := net.Interfaces()
@@ -91,8 +94,12 @@ func (m *multicast) interfaces() []net.Interface {
 			// Ignore point-to-point interfaces
 			continue
 		}
-		for _, expr := range m.core.ifceExpr {
-			if expr.MatchString(iface.Name) {
+		for _, expr := range exprs {
+			e, err := regexp.Compile(expr)
+			if err != nil {
+				panic(err)
+			}
+			if e.MatchString(iface.Name) {
 				interfaces = append(interfaces, iface)
 			}
 		}