diff --git a/irc/capability.go b/irc/capability.go
new file mode 100644
index 00000000..3ec4d3f9
--- /dev/null
+++ b/irc/capability.go
@@ -0,0 +1,116 @@
+package irc
+
+import (
+	"strings"
+)
+
+type CapSubCommand string
+
+const (
+	CAP_LS    CapSubCommand = "LS"
+	CAP_LIST  CapSubCommand = "LIST"
+	CAP_REQ   CapSubCommand = "REQ"
+	CAP_ACK   CapSubCommand = "ACK"
+	CAP_NAK   CapSubCommand = "NAK"
+	CAP_CLEAR CapSubCommand = "CLEAR"
+	CAP_END   CapSubCommand = "END"
+)
+
+// Capabilities are optional features a client may request from a server.
+type Capability string
+
+const (
+	MultiPrefix Capability = "multi-prefix"
+	SASL        Capability = "sasl"
+)
+
+var (
+	SupportedCapabilities = CapabilitySet{
+		MultiPrefix: true,
+	}
+)
+
+func (capability Capability) String() string {
+	return string(capability)
+}
+
+// CapModifiers are indicators showing the state of a capability after a REQ or
+// ACK.
+type CapModifier rune
+
+const (
+	Ack     CapModifier = '~'
+	Disable CapModifier = '-'
+	Sticky  CapModifier = '='
+)
+
+func (mod CapModifier) String() string {
+	return string(mod)
+}
+
+type CapState uint
+
+const (
+	CapNone        CapState = iota
+	CapNegotiating CapState = iota
+	CapNegotiated  CapState = iota
+)
+
+type CapabilitySet map[Capability]bool
+
+func (set CapabilitySet) String() string {
+	strs := make([]string, len(set))
+	index := 0
+	for capability := range set {
+		strs[index] = string(capability)
+		index += 1
+	}
+	return strings.Join(strs, " ")
+}
+
+func (set CapabilitySet) DisableString() string {
+	parts := make([]string, len(set))
+	index := 0
+	for capability := range set {
+		parts[index] = Disable.String() + capability.String()
+		index += 1
+	}
+	return strings.Join(parts, " ")
+}
+
+func (msg *CapCommand) HandleRegServer(server *Server) {
+	client := msg.Client()
+
+	switch msg.subCommand {
+	case CAP_LS:
+		client.capState = CapNegotiating
+		client.Reply(RplCap(client, CAP_LS, SupportedCapabilities))
+
+	case CAP_LIST:
+		client.Reply(RplCap(client, CAP_LIST, client.capabilities))
+
+	case CAP_REQ:
+		for capability := range msg.capabilities {
+			if !SupportedCapabilities[capability] {
+				client.Reply(RplCap(client, CAP_NAK, msg.capabilities))
+				return
+			}
+		}
+		for capability := range msg.capabilities {
+			client.capabilities[capability] = true
+		}
+		client.Reply(RplCap(client, CAP_ACK, msg.capabilities))
+
+	case CAP_CLEAR:
+		reply := RplCap(client, CAP_ACK, client.capabilities.DisableString())
+		client.capabilities = make(CapabilitySet)
+		client.Reply(reply)
+
+	case CAP_END:
+		client.capState = CapNegotiated
+		server.tryRegister(client)
+
+	default:
+		client.ErrInvalidCapCmd(msg.subCommand)
+	}
+}
diff --git a/irc/constants.go b/irc/constants.go
index cb0bde98..11af3983 100644
--- a/irc/constants.go
+++ b/irc/constants.go
@@ -196,14 +196,6 @@ const (
 	ERR_UMODEUNKNOWNFLAG  NumericCode = 501
 	ERR_USERSDONTMATCH    NumericCode = 502
 
-	CAP_LS    CapSubCommand = "LS"
-	CAP_LIST  CapSubCommand = "LIST"
-	CAP_REQ   CapSubCommand = "REQ"
-	CAP_ACK   CapSubCommand = "ACK"
-	CAP_NAK   CapSubCommand = "NAK"
-	CAP_CLEAR CapSubCommand = "CLEAR"
-	CAP_END   CapSubCommand = "END"
-
 	Add    ModeOp = '+'
 	List   ModeOp = '='
 	Remove ModeOp = '-'
@@ -234,28 +226,9 @@ const (
 	Secret          ChannelMode = 's' // flag, deprecated
 	UserLimit       ChannelMode = 'l' // flag arg
 	Voice           ChannelMode = 'v' // arg
-
-	MultiPrefix Capability = "multi-prefix"
-	SASL        Capability = "sasl"
-
-	Disable CapModifier = '-'
-	Ack     CapModifier = '~'
-	Sticky  CapModifier = '='
-)
-
-var (
-	SupportedCapabilities = CapabilitySet{
-		MultiPrefix: true,
-	}
 )
 
 const (
 	Registration Phase = iota
 	Normal       Phase = iota
 )
-
-const (
-	CapNone        CapState = iota
-	CapNegotiating CapState = iota
-	CapNegotiated  CapState = iota
-)
diff --git a/irc/server.go b/irc/server.go
index 66576743..bf4b150c 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -275,43 +275,6 @@ func (msg *ProxyCommand) HandleRegServer(server *Server) {
 	msg.Client().hostname = msg.hostname
 }
 
-func (msg *CapCommand) HandleRegServer(server *Server) {
-	client := msg.Client()
-
-	switch msg.subCommand {
-	case CAP_LS:
-		client.capState = CapNegotiating
-		client.Reply(RplCap(client, CAP_LS, SupportedCapabilities))
-
-	case CAP_LIST:
-		client.Reply(RplCap(client, CAP_LIST, client.capabilities))
-
-	case CAP_REQ:
-		for capability := range msg.capabilities {
-			if !SupportedCapabilities[capability] {
-				client.Reply(RplCap(client, CAP_NAK, msg.capabilities))
-				return
-			}
-		}
-		for capability := range msg.capabilities {
-			client.capabilities[capability] = true
-		}
-		client.Reply(RplCap(client, CAP_ACK, msg.capabilities))
-
-	case CAP_CLEAR:
-		reply := RplCap(client, CAP_ACK, client.capabilities.DisableString())
-		client.capabilities = make(CapabilitySet)
-		client.Reply(reply)
-
-	case CAP_END:
-		client.capState = CapNegotiated
-		server.tryRegister(client)
-
-	default:
-		client.ErrInvalidCapCmd(msg.subCommand)
-	}
-}
-
 func (m *NickCommand) HandleRegServer(s *Server) {
 	client := m.Client()
 	if !client.authorized {
diff --git a/irc/types.go b/irc/types.go
index 75938807..90631099 100644
--- a/irc/types.go
+++ b/irc/types.go
@@ -9,44 +9,6 @@ import (
 // simple types
 //
 
-type CapSubCommand string
-
-type Capability string
-
-func (capability Capability) String() string {
-	return string(capability)
-}
-
-type CapModifier rune
-
-func (mod CapModifier) String() string {
-	return string(mod)
-}
-
-type CapState uint
-
-type CapabilitySet map[Capability]bool
-
-func (set CapabilitySet) String() string {
-	strs := make([]string, len(set))
-	index := 0
-	for capability := range set {
-		strs[index] = string(capability)
-		index += 1
-	}
-	return strings.Join(strs, " ")
-}
-
-func (set CapabilitySet) DisableString() string {
-	parts := make([]string, len(set))
-	index := 0
-	for capability := range set {
-		parts[index] = Disable.String() + capability.String()
-		index += 1
-	}
-	return strings.Join(parts, " ")
-}
-
 // add, remove, list modes
 type ModeOp rune