diff --git a/irc/capability.go b/irc/capability.go
index 3ec4d3f9..27c12c79 100644
--- a/irc/capability.go
+++ b/irc/capability.go
@@ -7,13 +7,12 @@ import (
 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"
+	CAP_LS   CapSubCommand = "LS"
+	CAP_LIST CapSubCommand = "LIST"
+	CAP_REQ  CapSubCommand = "REQ"
+	CAP_ACK  CapSubCommand = "ACK"
+	CAP_NAK  CapSubCommand = "NAK"
+	CAP_END  CapSubCommand = "END"
 )
 
 // Capabilities are optional features a client may request from a server.
@@ -101,11 +100,6 @@ func (msg *CapCommand) HandleRegServer(server *Server) {
 		}
 		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)
@@ -114,3 +108,34 @@ func (msg *CapCommand) HandleRegServer(server *Server) {
 		client.ErrInvalidCapCmd(msg.subCommand)
 	}
 }
+
+func (msg *CapCommand) HandleServer(server *Server) {
+	client := msg.Client()
+
+	switch msg.subCommand {
+	case CAP_LS:
+		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_END:
+		// no-op after registration performed
+		return
+
+	default:
+		client.ErrInvalidCapCmd(msg.subCommand)
+	}
+}