diff --git a/spec/std/socket/udp_socket_spec.cr b/spec/std/socket/udp_socket_spec.cr
index 3c071f9bacbe..8b57f0c5320c 100644
--- a/spec/std/socket/udp_socket_spec.cr
+++ b/spec/std/socket/udp_socket_spec.cr
@@ -1,8 +1,9 @@
 require "./spec_helper"
+require "../../support/errno"
 require "socket"
 
 describe UDPSocket do
-  each_ip_family do |family, address|
+  each_ip_family do |family, address, unspecified_address|
     it "#bind" do
       port = unused_local_port
       socket = UDPSocket.new(family)
@@ -52,6 +53,63 @@ describe UDPSocket do
       client.close
       server.close
     end
+
+    if {{ flag?(:darwin) }} && family == Socket::Family::INET6
+      # Darwin is failing to join IPv6 multicast groups on older versions.
+      # However this is known to work on macOS Mojave with Darwin 18.2.0.
+      # Darwin also has a bug that prevents selecting the "default" interface.
+      # https://lists.apple.com/archives/darwin-kernel/2014/Mar/msg00012.html
+      pending "joins and transmits to multicast groups"
+    else
+      it "joins and transmits to multicast groups" do
+        udp = UDPSocket.new(family)
+        udp.bind(unspecified_address, 2000)
+
+        udp.multicast_loopback = false
+        udp.multicast_loopback?.should eq(false)
+
+        udp.multicast_hops = 4
+        udp.multicast_hops.should eq(4)
+        udp.multicast_hops = 0
+        udp.multicast_hops.should eq(0)
+
+        addr = case family
+               when Socket::Family::INET
+                 expect_raises(Socket::Error, "Unsupported IP address family: INET. For use with IPv6 only") do
+                   udp.multicast_interface 0
+                 end
+                 udp.multicast_interface Socket::IPAddress.new(unspecified_address, 0)
+
+                 Socket::IPAddress.new("224.0.0.254", 2000)
+               when Socket::Family::INET6
+                 expect_raises(Socket::Error, "Unsupported IP address family: INET6. For use with IPv4 only") do
+                   udp.multicast_interface(Socket::IPAddress.new(unspecified_address, 0))
+                 end
+                 udp.multicast_interface(0)
+
+                 Socket::IPAddress.new("ff02::102", 2000)
+               else
+                 raise "Unsupported IP address family: #{family}"
+               end
+
+        udp.join_group(addr)
+        udp.multicast_loopback = true
+        udp.multicast_loopback?.should eq(true)
+
+        udp.send("testing", addr)
+        udp.receive[0].should eq("testing")
+
+        udp.leave_group(addr)
+        udp.send("testing", addr)
+
+        # Test that nothing was received after leaving the multicast group
+        spawn do
+          sleep 100.milliseconds
+          udp.close
+        end
+        expect_raises_errno(Errno::EBADF, "Error receiving datagram: Bad file descriptor") { udp.receive }
+      end
+    end
   end
 
   {% if flag?(:linux) %}
diff --git a/src/lib_c/aarch64-linux-gnu/c/netinet/in.cr b/src/lib_c/aarch64-linux-gnu/c/netinet/in.cr
index 466c5dab53e7..b934d735f80b 100644
--- a/src/lib_c/aarch64-linux-gnu/c/netinet/in.cr
+++ b/src/lib_c/aarch64-linux-gnu/c/netinet/in.cr
@@ -3,6 +3,7 @@ require "../stdint"
 
 lib LibC
   IPPROTO_IP   =   0
+  IPPROTO_IPV6 =  41
   IPPROTO_ICMP =   1
   IPPROTO_RAW  = 255
   IPPROTO_TCP  =   6
@@ -39,4 +40,29 @@ lib LibC
     sin6_addr : In6Addr
     sin6_scope_id : UInt32T
   end
+
+  IP_MULTICAST_IF   = 32
+  IPV6_MULTICAST_IF = 17
+
+  IP_MULTICAST_TTL    = 33
+  IPV6_MULTICAST_HOPS = 18
+
+  IP_MULTICAST_LOOP   = 34
+  IPV6_MULTICAST_LOOP = 19
+
+  IP_ADD_MEMBERSHIP = 35
+  IPV6_JOIN_GROUP   = 20
+
+  IP_DROP_MEMBERSHIP = 36
+  IPV6_LEAVE_GROUP   = 21
+
+  struct IpMreq
+    imr_multiaddr : InAddr
+    imr_interface : InAddr
+  end
+
+  struct Ipv6Mreq
+    ipv6mr_multiaddr : In6Addr
+    ipv6mr_interface : UInt
+  end
 end
diff --git a/src/lib_c/aarch64-linux-musl/c/netinet/in.cr b/src/lib_c/aarch64-linux-musl/c/netinet/in.cr
index 464da8a3fe4d..c497075effaf 100644
--- a/src/lib_c/aarch64-linux-musl/c/netinet/in.cr
+++ b/src/lib_c/aarch64-linux-musl/c/netinet/in.cr
@@ -3,6 +3,7 @@ require "../stdint"
 
 lib LibC
   IPPROTO_IP   =   0
+  IPPROTO_IPV6 =  41
   IPPROTO_ICMP =   1
   IPPROTO_RAW  = 255
   IPPROTO_TCP  =   6
@@ -39,4 +40,29 @@ lib LibC
     sin6_addr : In6Addr
     sin6_scope_id : UInt32T
   end
+
+  IP_MULTICAST_IF   = 32
+  IPV6_MULTICAST_IF = 17
+
+  IP_MULTICAST_TTL    = 33
+  IPV6_MULTICAST_HOPS = 18
+
+  IP_MULTICAST_LOOP   = 34
+  IPV6_MULTICAST_LOOP = 19
+
+  IP_ADD_MEMBERSHIP = 35
+  IPV6_JOIN_GROUP   = 20
+
+  IP_DROP_MEMBERSHIP = 36
+  IPV6_LEAVE_GROUP   = 21
+
+  struct IpMreq
+    imr_multiaddr : InAddr
+    imr_interface : InAddr
+  end
+
+  struct Ipv6Mreq
+    ipv6mr_multiaddr : In6Addr
+    ipv6mr_interface : UInt
+  end
 end
diff --git a/src/lib_c/arm-linux-gnueabihf/c/netinet/in.cr b/src/lib_c/arm-linux-gnueabihf/c/netinet/in.cr
index 466c5dab53e7..b934d735f80b 100644
--- a/src/lib_c/arm-linux-gnueabihf/c/netinet/in.cr
+++ b/src/lib_c/arm-linux-gnueabihf/c/netinet/in.cr
@@ -3,6 +3,7 @@ require "../stdint"
 
 lib LibC
   IPPROTO_IP   =   0
+  IPPROTO_IPV6 =  41
   IPPROTO_ICMP =   1
   IPPROTO_RAW  = 255
   IPPROTO_TCP  =   6
@@ -39,4 +40,29 @@ lib LibC
     sin6_addr : In6Addr
     sin6_scope_id : UInt32T
   end
+
+  IP_MULTICAST_IF   = 32
+  IPV6_MULTICAST_IF = 17
+
+  IP_MULTICAST_TTL    = 33
+  IPV6_MULTICAST_HOPS = 18
+
+  IP_MULTICAST_LOOP   = 34
+  IPV6_MULTICAST_LOOP = 19
+
+  IP_ADD_MEMBERSHIP = 35
+  IPV6_JOIN_GROUP   = 20
+
+  IP_DROP_MEMBERSHIP = 36
+  IPV6_LEAVE_GROUP   = 21
+
+  struct IpMreq
+    imr_multiaddr : InAddr
+    imr_interface : InAddr
+  end
+
+  struct Ipv6Mreq
+    ipv6mr_multiaddr : In6Addr
+    ipv6mr_interface : UInt
+  end
 end
diff --git a/src/lib_c/i386-linux-gnu/c/netinet/in.cr b/src/lib_c/i386-linux-gnu/c/netinet/in.cr
index 466c5dab53e7..b934d735f80b 100644
--- a/src/lib_c/i386-linux-gnu/c/netinet/in.cr
+++ b/src/lib_c/i386-linux-gnu/c/netinet/in.cr
@@ -3,6 +3,7 @@ require "../stdint"
 
 lib LibC
   IPPROTO_IP   =   0
+  IPPROTO_IPV6 =  41
   IPPROTO_ICMP =   1
   IPPROTO_RAW  = 255
   IPPROTO_TCP  =   6
@@ -39,4 +40,29 @@ lib LibC
     sin6_addr : In6Addr
     sin6_scope_id : UInt32T
   end
+
+  IP_MULTICAST_IF   = 32
+  IPV6_MULTICAST_IF = 17
+
+  IP_MULTICAST_TTL    = 33
+  IPV6_MULTICAST_HOPS = 18
+
+  IP_MULTICAST_LOOP   = 34
+  IPV6_MULTICAST_LOOP = 19
+
+  IP_ADD_MEMBERSHIP = 35
+  IPV6_JOIN_GROUP   = 20
+
+  IP_DROP_MEMBERSHIP = 36
+  IPV6_LEAVE_GROUP   = 21
+
+  struct IpMreq
+    imr_multiaddr : InAddr
+    imr_interface : InAddr
+  end
+
+  struct Ipv6Mreq
+    ipv6mr_multiaddr : In6Addr
+    ipv6mr_interface : UInt
+  end
 end
diff --git a/src/lib_c/i386-linux-musl/c/netinet/in.cr b/src/lib_c/i386-linux-musl/c/netinet/in.cr
index 464da8a3fe4d..c497075effaf 100644
--- a/src/lib_c/i386-linux-musl/c/netinet/in.cr
+++ b/src/lib_c/i386-linux-musl/c/netinet/in.cr
@@ -3,6 +3,7 @@ require "../stdint"
 
 lib LibC
   IPPROTO_IP   =   0
+  IPPROTO_IPV6 =  41
   IPPROTO_ICMP =   1
   IPPROTO_RAW  = 255
   IPPROTO_TCP  =   6
@@ -39,4 +40,29 @@ lib LibC
     sin6_addr : In6Addr
     sin6_scope_id : UInt32T
   end
+
+  IP_MULTICAST_IF   = 32
+  IPV6_MULTICAST_IF = 17
+
+  IP_MULTICAST_TTL    = 33
+  IPV6_MULTICAST_HOPS = 18
+
+  IP_MULTICAST_LOOP   = 34
+  IPV6_MULTICAST_LOOP = 19
+
+  IP_ADD_MEMBERSHIP = 35
+  IPV6_JOIN_GROUP   = 20
+
+  IP_DROP_MEMBERSHIP = 36
+  IPV6_LEAVE_GROUP   = 21
+
+  struct IpMreq
+    imr_multiaddr : InAddr
+    imr_interface : InAddr
+  end
+
+  struct Ipv6Mreq
+    ipv6mr_multiaddr : In6Addr
+    ipv6mr_interface : UInt
+  end
 end
diff --git a/src/lib_c/x86_64-darwin/c/netinet/in.cr b/src/lib_c/x86_64-darwin/c/netinet/in.cr
index 88d64a2b23cc..02cb5721dc21 100644
--- a/src/lib_c/x86_64-darwin/c/netinet/in.cr
+++ b/src/lib_c/x86_64-darwin/c/netinet/in.cr
@@ -3,6 +3,7 @@ require "../stdint"
 
 lib LibC
   IPPROTO_IP   =   0
+  IPPROTO_IPV6 =  41
   IPPROTO_ICMP =   1
   IPPROTO_RAW  = 255
   IPPROTO_TCP  =   6
@@ -41,4 +42,29 @@ lib LibC
     sin6_addr : In6Addr
     sin6_scope_id : UInt
   end
+
+  IP_MULTICAST_IF   = 9
+  IPV6_MULTICAST_IF = 9
+
+  IP_MULTICAST_TTL    = 10
+  IPV6_MULTICAST_HOPS = 10
+
+  IP_MULTICAST_LOOP   = 11
+  IPV6_MULTICAST_LOOP = 11
+
+  IP_ADD_MEMBERSHIP = 12
+  IPV6_JOIN_GROUP   = 12
+
+  IP_DROP_MEMBERSHIP = 13
+  IPV6_LEAVE_GROUP   = 13
+
+  struct IpMreq
+    imr_multiaddr : InAddr
+    imr_interface : InAddr
+  end
+
+  struct Ipv6Mreq
+    ipv6mr_multiaddr : In6Addr
+    ipv6mr_interface : UInt
+  end
 end
diff --git a/src/lib_c/x86_64-freebsd/c/netinet/in.cr b/src/lib_c/x86_64-freebsd/c/netinet/in.cr
index 698b00a5bede..0f09b0e39ca5 100644
--- a/src/lib_c/x86_64-freebsd/c/netinet/in.cr
+++ b/src/lib_c/x86_64-freebsd/c/netinet/in.cr
@@ -3,6 +3,7 @@ require "../stdint"
 
 lib LibC
   IPPROTO_IP   =   0
+  IPPROTO_IPV6 =  41
   IPPROTO_ICMP =   1
   IPPROTO_RAW  = 255
   IPPROTO_TCP  =   6
@@ -41,4 +42,29 @@ lib LibC
     sin6_addr : In6Addr
     sin6_scope_id : UInt32T
   end
+
+  IP_MULTICAST_IF   = 9
+  IPV6_MULTICAST_IF = 9
+
+  IP_MULTICAST_TTL    = 10
+  IPV6_MULTICAST_HOPS = 10
+
+  IP_MULTICAST_LOOP   = 11
+  IPV6_MULTICAST_LOOP = 11
+
+  IP_ADD_MEMBERSHIP = 12
+  IPV6_JOIN_GROUP   = 12
+
+  IP_DROP_MEMBERSHIP = 13
+  IPV6_LEAVE_GROUP   = 13
+
+  struct IpMreq
+    imr_multiaddr : InAddr
+    imr_interface : InAddr
+  end
+
+  struct Ipv6Mreq
+    ipv6mr_multiaddr : In6Addr
+    ipv6mr_interface : UInt
+  end
 end
diff --git a/src/lib_c/x86_64-linux-gnu/c/netinet/in.cr b/src/lib_c/x86_64-linux-gnu/c/netinet/in.cr
index 466c5dab53e7..b934d735f80b 100644
--- a/src/lib_c/x86_64-linux-gnu/c/netinet/in.cr
+++ b/src/lib_c/x86_64-linux-gnu/c/netinet/in.cr
@@ -3,6 +3,7 @@ require "../stdint"
 
 lib LibC
   IPPROTO_IP   =   0
+  IPPROTO_IPV6 =  41
   IPPROTO_ICMP =   1
   IPPROTO_RAW  = 255
   IPPROTO_TCP  =   6
@@ -39,4 +40,29 @@ lib LibC
     sin6_addr : In6Addr
     sin6_scope_id : UInt32T
   end
+
+  IP_MULTICAST_IF   = 32
+  IPV6_MULTICAST_IF = 17
+
+  IP_MULTICAST_TTL    = 33
+  IPV6_MULTICAST_HOPS = 18
+
+  IP_MULTICAST_LOOP   = 34
+  IPV6_MULTICAST_LOOP = 19
+
+  IP_ADD_MEMBERSHIP = 35
+  IPV6_JOIN_GROUP   = 20
+
+  IP_DROP_MEMBERSHIP = 36
+  IPV6_LEAVE_GROUP   = 21
+
+  struct IpMreq
+    imr_multiaddr : InAddr
+    imr_interface : InAddr
+  end
+
+  struct Ipv6Mreq
+    ipv6mr_multiaddr : In6Addr
+    ipv6mr_interface : UInt
+  end
 end
diff --git a/src/lib_c/x86_64-linux-musl/c/netinet/in.cr b/src/lib_c/x86_64-linux-musl/c/netinet/in.cr
index 464da8a3fe4d..c497075effaf 100644
--- a/src/lib_c/x86_64-linux-musl/c/netinet/in.cr
+++ b/src/lib_c/x86_64-linux-musl/c/netinet/in.cr
@@ -3,6 +3,7 @@ require "../stdint"
 
 lib LibC
   IPPROTO_IP   =   0
+  IPPROTO_IPV6 =  41
   IPPROTO_ICMP =   1
   IPPROTO_RAW  = 255
   IPPROTO_TCP  =   6
@@ -39,4 +40,29 @@ lib LibC
     sin6_addr : In6Addr
     sin6_scope_id : UInt32T
   end
+
+  IP_MULTICAST_IF   = 32
+  IPV6_MULTICAST_IF = 17
+
+  IP_MULTICAST_TTL    = 33
+  IPV6_MULTICAST_HOPS = 18
+
+  IP_MULTICAST_LOOP   = 34
+  IPV6_MULTICAST_LOOP = 19
+
+  IP_ADD_MEMBERSHIP = 35
+  IPV6_JOIN_GROUP   = 20
+
+  IP_DROP_MEMBERSHIP = 36
+  IPV6_LEAVE_GROUP   = 21
+
+  struct IpMreq
+    imr_multiaddr : InAddr
+    imr_interface : InAddr
+  end
+
+  struct Ipv6Mreq
+    ipv6mr_multiaddr : In6Addr
+    ipv6mr_interface : UInt
+  end
 end
diff --git a/src/lib_c/x86_64-openbsd/c/netinet/in.cr b/src/lib_c/x86_64-openbsd/c/netinet/in.cr
index 9e5ab45a2318..f5b968cae094 100644
--- a/src/lib_c/x86_64-openbsd/c/netinet/in.cr
+++ b/src/lib_c/x86_64-openbsd/c/netinet/in.cr
@@ -3,6 +3,7 @@ require "../stdint"
 
 lib LibC
   IPPROTO_IP   =   0
+  IPPROTO_IPV6 =  41
   IPPROTO_ICMP =   1
   IPPROTO_RAW  = 255
   IPPROTO_TCP  =   6
@@ -41,4 +42,29 @@ lib LibC
     sin6_addr : In6Addr
     sin6_scope_id : UInt32T
   end
+
+  IP_MULTICAST_IF   = 9
+  IPV6_MULTICAST_IF = 9
+
+  IP_MULTICAST_TTL    = 10
+  IPV6_MULTICAST_HOPS = 10
+
+  IP_MULTICAST_LOOP   = 11
+  IPV6_MULTICAST_LOOP = 11
+
+  IP_ADD_MEMBERSHIP = 12
+  IPV6_JOIN_GROUP   = 12
+
+  IP_DROP_MEMBERSHIP = 13
+  IPV6_LEAVE_GROUP   = 13
+
+  struct IpMreq
+    imr_multiaddr : InAddr
+    imr_interface : InAddr
+  end
+
+  struct Ipv6Mreq
+    ipv6mr_multiaddr : In6Addr
+    ipv6mr_interface : UInt
+  end
 end
diff --git a/src/socket/udp_socket.cr b/src/socket/udp_socket.cr
index 503588cdb940..712d02f2df7f 100644
--- a/src/socket/udp_socket.cr
+++ b/src/socket/udp_socket.cr
@@ -92,4 +92,148 @@ class UDPSocket < IPSocket
     bytes_read, sockaddr, addrlen = recvfrom(message)
     {bytes_read, IPAddress.from(sockaddr, addrlen)}
   end
+
+  # Reports whether transmitted multicast packets should be copied and sent
+  # back to the originator.
+  def multicast_loopback?
+    case @family
+    when Family::INET
+      getsockopt_bool LibC::IP_MULTICAST_LOOP, LibC::IPPROTO_IP
+    when Family::INET6
+      getsockopt_bool LibC::IPV6_MULTICAST_LOOP, LibC::IPPROTO_IPV6
+    else
+      raise Socket::Error.new "Unsupported IP address family: #{@family}"
+    end
+  end
+
+  # Sets whether transmitted multicast packets should be copied and sent back
+  # to the originator, if the host has joined the multicast group.
+  def multicast_loopback=(val : Bool)
+    case @family
+    when Family::INET
+      setsockopt_bool LibC::IP_MULTICAST_LOOP, val, LibC::IPPROTO_IP
+    when Family::INET6
+      setsockopt_bool LibC::IPV6_MULTICAST_LOOP, val, LibC::IPPROTO_IPV6
+    else
+      raise Socket::Error.new "Unsupported IP address family: #{@family}"
+    end
+  end
+
+  # Returns the current value of the `hoplimit` field on uni-cast packets.
+  # Datagrams with a `hoplimit` of `1` are not forwarded beyond the local network.
+  # Multicast datagrams with a `hoplimit` of `0` will not be transmitted on any
+  # network, but may be delivered locally if the sending host belongs to the
+  # destination group and multicast loopback is enabled.
+  def multicast_hops
+    case @family
+    when Family::INET
+      getsockopt LibC::IP_MULTICAST_TTL, 0, LibC::IPPROTO_IP
+    when Family::INET6
+      getsockopt LibC::IPV6_MULTICAST_HOPS, 0, LibC::IPPROTO_IPV6
+    else
+      raise Socket::Error.new "Unsupported IP address family: #{@family}"
+    end
+  end
+
+  # The multicast hops option controls the `hoplimit` field on uni-cast packets.
+  # If `-1` is specified, the kernel will use a default value.
+  # If a value of `0` to `255` is specified, the packet will have the specified
+  # value as `hoplimit`. Other values are considered invalid and `Errno` will be raised.
+  # Datagrams with a `hoplimit` of `1` are not forwarded beyond the local network.
+  # Multicast datagrams with a `hoplimit` of `0` will not be transmitted on any
+  # network, but may be delivered locally if the sending host belongs to the
+  # destination group and multicast loopback is enabled.
+  def multicast_hops=(val : Int)
+    case @family
+    when Family::INET
+      setsockopt LibC::IP_MULTICAST_TTL, val, LibC::IPPROTO_IP
+    when Family::INET6
+      setsockopt LibC::IPV6_MULTICAST_HOPS, val, LibC::IPPROTO_IPV6
+    else
+      raise Socket::Error.new "Unsupported IP address family: #{@family}"
+    end
+    val
+  end
+
+  # For hosts with multiple interfaces, each multicast transmission is sent
+  # from the primary network interface. This function overrides the default
+  # IPv4 interface address for subsequent transmissions. Setting the interface
+  # to `0.0.0.0` will select the default interface.
+  # Raises `Socket::Error` unless the socket is IPv4 and an IPv4 address is provided.
+  def multicast_interface(address : IPAddress)
+    if @family == Family::INET
+      if addr = address.@addr4
+        setsockopt LibC::IP_MULTICAST_IF, addr, LibC::IPPROTO_IP
+      else
+        raise Socket::Error.new "Expecting an IPv4 interface address. Address provided: #{address.address}"
+      end
+    else
+      raise Socket::Error.new "Unsupported IP address family: #{@family}. For use with IPv4 only"
+    end
+  end
+
+  # For hosts with multiple interfaces, each multicast transmission is sent
+  # from the primary network interface. This function overrides the default
+  # IPv6 interface for subsequent transmissions. Setting the interface to
+  # index `0` will select the default interface.
+  def multicast_interface(index : UInt32)
+    if @family == Family::INET6
+      setsockopt LibC::IPV6_MULTICAST_IF, index, LibC::IPPROTO_IPV6
+    else
+      raise Socket::Error.new "Unsupported IP address family: #{@family}. For use with IPv6 only"
+    end
+  end
+
+  # A host must become a member of a multicast group before it can receive
+  # datagrams sent to the group.
+  # Raises `Socket::Error` if an incompatible address is provided.
+  def join_group(address : IPAddress)
+    case @family
+    when Family::INET
+      group_modify(address, LibC::IP_ADD_MEMBERSHIP)
+    when Family::INET6
+      group_modify(address, LibC::IPV6_JOIN_GROUP)
+    else
+      raise Socket::Error.new "Unsupported IP address family: #{@family}"
+    end
+  end
+
+  # Drops membership to the specified group. Memberships are automatically
+  # dropped when the socket is closed or the process exits.
+  # Raises `Socket::Error` if an incompatible address is provided.
+  def leave_group(address : IPAddress)
+    case @family
+    when Family::INET
+      group_modify(address, LibC::IP_DROP_MEMBERSHIP)
+    when Family::INET6
+      group_modify(address, LibC::IPV6_LEAVE_GROUP)
+    else
+      raise Socket::Error.new "Unsupported IP address family: #{@family}"
+    end
+  end
+
+  private def group_modify(ip, operation)
+    case @family
+    when Family::INET
+      if ip_addr = ip.@addr4
+        req = LibC::IpMreq.new
+        req.imr_multiaddr = ip_addr
+
+        setsockopt operation, req, LibC::IPPROTO_IP
+      else
+        raise Socket::Error.new "Expecting an IPv4 multicast address. Address provided: #{ip.address}"
+      end
+    when Family::INET6
+      if ip_addr = ip.@addr6
+        req = LibC::Ipv6Mreq.new
+        req.ipv6mr_multiaddr = ip_addr
+
+        setsockopt operation, req, LibC::IPPROTO_IPV6
+      else
+        raise Socket::Error.new "Expecting an IPv6 multicast address. Address provided: #{ip.address}"
+      end
+    else
+      raise Socket::Error.new "Unsupported IP address family: #{@family}"
+    end
+  end
 end