diff --git a/better-dns.go b/better-dns.go
index 73d1f7d..43b10c9 100644
--- a/better-dns.go
+++ b/better-dns.go
@@ -12,6 +12,7 @@ import (
 	"os/signal"
 	"strconv"
 	"strings"
+	"sync"
 	"syscall"
 	"time"
 )
@@ -91,10 +92,17 @@ func loadLists() {
 		"https://pgl.yoyo.org/adservers/serverlist.php?hostformat=hosts&showintro=0&mimetype=plaintext",
 	}
 
+	wg := &sync.WaitGroup{}
 	for i := range urls {
-		blockFromURL(urls[i])
+		wg.Add(1)
+		go func(url string) {
+			blockFromURL(url)
+			wg.Done()
+		}(urls[i])
 	}
 
+	wg.Wait()
+
 	server.LogLists()
 }
 
diff --git a/server/filter.go b/server/filter.go
index 26ed64f..7a43ba9 100644
--- a/server/filter.go
+++ b/server/filter.go
@@ -5,10 +5,12 @@ import (
 	"github.com/miekg/dns"
 	log "github.com/sirupsen/logrus"
 	"net"
+	"sync"
 )
 
 var blockedEntries = map[string]*shared.BlockEntry{}
 var listEntries = map[string]int64{}
+var blockListMutex = &sync.Mutex{}
 
 func filter(req *dns.Msg) *shared.BlockEntry {
 	question := req.Question[0]
@@ -63,6 +65,10 @@ func AddBlockedEntry(name string, list string) {
 		name = name + "."
 	}
 
+	// Called from multiple goroutines so making the map and list processing safe
+	blockListMutex.Lock()
+	defer blockListMutex.Unlock()
+
 	blockedEntries[name] = &shared.BlockEntry{Src: list}
 
 	old, ok := listEntries[list]
diff --git a/shared/dnsservers_darwin.go b/shared/dnsservers_darwin.go
index a8abda6..59f5657 100644
--- a/shared/dnsservers_darwin.go
+++ b/shared/dnsservers_darwin.go
@@ -21,7 +21,7 @@ func RememberDnsServers() {
 	for _, line := range lines {
 		line := strings.TrimSpace(line)
 
-		// Configuration for interface "Local Area Connection* 1"
+		// Hardware Port: Ethernet
 		if strings.HasPrefix(line, "Hardware Port: ") {
 			parts := strings.SplitN(line, ": ", 2)
 			interfaces = append(interfaces, parts[1])
@@ -32,28 +32,44 @@ func RememberDnsServers() {
 }
 
 func UpdateDnsServers() {
+	wg := &sync.WaitGroup{}
 	for _, iface := range interfaces {
-		cmd := exec.Command("networksetup", "-setdnsservers", iface, "127.0.0.1")
-		output, err := cmd.CombinedOutput()
-		log.Error(strings.TrimSpace(string(output[:])))
-		if err != nil {
-			log.Errorf("Error setting %s DNS servers: %s", iface, err)
-		} else {
-			log.Debugf("%s now using 127.0.0.1 for DNS", iface)
-		}
+		wg.Add(1)
+
+		go func(iface string) {
+			cmd := exec.Command("networksetup", "-setdnsservers", iface, "127.0.0.1")
+			output, err := cmd.CombinedOutput()
+			log.Error(strings.TrimSpace(string(output[:])))
+			if err != nil {
+				log.Errorf("Error setting %s DNS servers: %s", iface, err)
+			} else {
+				log.Debugf("%s now using 127.0.0.1 for DNS", iface)
+			}
+			wg.Done()
+		}(iface)
 	}
+
+	wg.Wait()
 }
 
 func RestoreDnsServers() {
+	wg := &sync.WaitGroup{}
 	for _, iface := range interfaces {
-		cmd := exec.Command("networksetup", "-setdnsservers", iface, "empty")
-		output, err := cmd.CombinedOutput()
-		if err != nil {
-			log.Errorf("Error restoring %s DNS servers: %s", iface, err)
-			log.Errorf("Try manually with: networksetup -setdnsservers %s empty", iface)
-			log.Error(strings.TrimSpace(string(output[:])))
-		} else {
-			log.Debugf("%s now using DNS servers set by DHCP", iface)
-		}
+		wg.Add(1)
+
+		go func(iface string) {
+			cmd := exec.Command("networksetup", "-setdnsservers", iface, "empty")
+			output, err := cmd.CombinedOutput()
+			if err != nil {
+				log.Errorf("Error restoring %s DNS servers: %s", iface, err)
+				log.Errorf("Try manually with: networksetup -setdnsservers %s empty", iface)
+				log.Error(strings.TrimSpace(string(output[:])))
+			} else {
+				log.Debugf("%s now using DNS servers set by DHCP", iface)
+			}
+			wg.Done()
+		}(iface)
 	}
+
+	wg.Wait()
 }
diff --git a/shared/dnsservers_windows.go b/shared/dnsservers_windows.go
index 1075694..16e4b26 100644
--- a/shared/dnsservers_windows.go
+++ b/shared/dnsservers_windows.go
@@ -5,6 +5,7 @@ import (
 	log "github.com/sirupsen/logrus"
 	"os/exec"
 	"strings"
+	"sync"
 )
 
 var interfaces = []string{}
@@ -43,32 +44,48 @@ func RememberDnsServers() {
 }
 
 func UpdateDnsServers() {
+	wg := &sync.WaitGroup{}
 	for _, iface := range interfaces {
-		iface = fmt.Sprintf("\"%s\"", iface)
-		ps := fmt.Sprintf("Set-DnsClientServerAddress -InterfaceAlias %s -ServerAddresses (\"127.0.0.1\")", iface)
-		cmd := exec.Command("powershell.exe", "-Command", ps)
-		output, err := cmd.CombinedOutput()
-		log.Error(strings.TrimSpace(string(output[:])))
-		if err != nil {
-			log.Errorf("Error setting %s DNS servers: %s", iface, err)
-		} else {
-			log.Debugf("%s now using 127.0.0.1 for DNS", iface)
-		}
+		wg.Add(1)
+
+		go func(iface string) {
+			iface = fmt.Sprintf("\"%s\"", iface)
+			ps := fmt.Sprintf("Set-DnsClientServerAddress -InterfaceAlias %s -ServerAddresses (\"127.0.0.1\")", iface)
+			cmd := exec.Command("powershell.exe", "-Command", ps)
+			output, err := cmd.CombinedOutput()
+			if err != nil {
+				log.Errorf("Error setting %s DNS servers: %s", iface, err)
+				log.Errorf("Output was: %s", output)
+			} else {
+				log.Debugf("%s now using 127.0.0.1 for DNS", iface)
+			}
+			wg.Done()
+		}(iface)
 	}
+
+	wg.Wait()
 }
 
 func RestoreDnsServers() {
+	wg := &sync.WaitGroup{}
 	for _, iface := range interfaces {
-		iface = fmt.Sprintf("\"%s\"", iface)
-		ps := fmt.Sprintf("Set-DnsClientServerAddress -InterfaceAlias %s -ResetServerAddresses", iface)
-		cmd := exec.Command("powershell.exe", "-Command", ps)
-		output, err := cmd.CombinedOutput()
-		if err != nil {
-			log.Errorf("Error restoring %s DNS servers: %s", iface, err)
-			log.Errorf("Try manually with: netsh interface ipv4 set dnsservers name=%s source=dhcp", iface)
-			log.Error(strings.TrimSpace(string(output[:])))
-		} else {
-			log.Debugf("%s now using DNS servers set by DHCP", iface)
-		}
+		wg.Add(1)
+
+		go func(iface string) {
+			iface = fmt.Sprintf("\"%s\"", iface)
+			ps := fmt.Sprintf("Set-DnsClientServerAddress -InterfaceAlias %s -ResetServerAddresses", iface)
+			cmd := exec.Command("powershell.exe", "-Command", ps)
+			output, err := cmd.CombinedOutput()
+			if err != nil {
+				log.Errorf("Error restoring %s DNS servers: %s", iface, err)
+				log.Errorf("Try manually with: netsh interface ipv4 set dnsservers name=%s source=dhcp", iface)
+				log.Error(strings.TrimSpace(string(output[:])))
+			} else {
+				log.Debugf("%s now using DNS servers set by DHCP", iface)
+			}
+			wg.Done()
+		}(iface)
 	}
+
+	wg.Wait()
 }