diff --git a/lib/client.js b/lib/client.js
index de7660b..8dea847 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -47,6 +47,7 @@ export default class Client extends EventTarget {
 	autoReconnect = true;
 	reconnectTimeoutID = null;
 	pendingHistory = Promise.resolve(null);
+	cm = irc.CaseMapping.RFC1459;
 
 	constructor(params) {
 		super();
@@ -166,7 +167,18 @@ export default class Client extends EventTarget {
 			break;
 		case irc.RPL_ISUPPORT:
 			var tokens = msg.params.slice(1, -1);
-			irc.parseISUPPORT(tokens, this.isupport);
+			var changed = irc.parseISUPPORT(tokens, this.isupport);
+			if (changed.indexOf("CASEMAPPING") >= 0) {
+				this.setCaseMapping(this.isupport.get("CASEMAPPING"));
+			}
+			break;
+		case irc.RPL_ENDOFMOTD:
+		case irc.ERR_NOMOTD:
+			// These messages are used to indicate the end of the ISUPPORT list
+			if (!this.isupport.has("CASEMAPPING")) {
+				// Server didn't send any CASEMAPPING token, assume RFC 1459
+				this.setCaseMapping("rfc1459");
+			}
 			break;
 		case "CAP":
 			this.handleCap(msg);
@@ -378,6 +390,14 @@ export default class Client extends EventTarget {
 		console.debug("Sent:", msg);
 	}
 
+	setCaseMapping(name) {
+		this.cm = irc.CaseMapping.byName(name);
+		if (!this.cm) {
+			console.error("Unsupported case-mapping '" + name + "', falling back to RFC 1459");
+			this.cm = irc.CaseMapping.RFC1459;
+		}
+	}
+
 	/* Execute a command that expects a response. `done` is called with message
 	 * events until it returns a truthy value. */
 	roundtrip(msg, done) {
diff --git a/lib/irc.js b/lib/irc.js
index b540051..5093e93 100644
--- a/lib/irc.js
+++ b/lib/irc.js
@@ -11,6 +11,7 @@ export const RPL_TOPICWHOTIME = "333";
 export const RPL_WHOREPLY = "352";
 export const RPL_NAMREPLY = "353";
 export const RPL_ENDOFNAMES = "366";
+export const RPL_ENDOFMOTD = "376";
 export const ERR_NOMOTD = "422";
 export const ERR_ERRONEUSNICKNAME = "432";
 export const ERR_NICKNAMEINUSE = "433";