Index: src/XMPPConnection.m
==================================================================
--- src/XMPPConnection.m
+++ src/XMPPConnection.m
@@ -22,10 +22,11 @@
  */
 
 #include <assert.h>
 
 #include <stringprep.h>
+#include <idna.h>
 
 #import "XMPPConnection.h"
 #import "XMPPStanza.h"
 #import "XMPPJID.h"
 #import "XMPPIQ.h"
@@ -114,18 +115,19 @@
 
 - (void)setServer: (OFString*)server_
 {
 	OFString *old = server;
 	char *srv;
-	Stringprep_rc rc;
-
-	if ((rc = stringprep_profile([server_ cString], &srv,
-	    "Nameprep", 0)) != STRINGPREP_OK)
-		@throw [XMPPStringPrepFailedException newWithClass: isa
-							connection: self
-							   profile: @"Nameprep"
-							    string: server_];
+	Idna_rc rc;
+
+	if ((rc = idna_to_ascii_8z([server_ cString],
+	    &srv, IDNA_USE_STD3_ASCII_RULES)) != IDNA_SUCCESS)
+		@throw [XMPPIDNATranslationFailedException
+		 newWithClass: isa
+		   connection: self
+		    operation: @"ToASCII"
+		       string: server_];
 
 	@try {
 		server = [[OFString alloc] initWithCString: srv];
 	} @finally {
 		free(srv);

Index: src/XMPPExceptions.h
==================================================================
--- src/XMPPExceptions.h
+++ src/XMPPExceptions.h
@@ -52,5 +52,23 @@
 - initWithClass: (Class)class_
      connection: (XMPPConnection*)conn
 	profile: (OFString*)profile
 	 string: (OFString*)string;
 @end
+
+@interface XMPPIDNATranslationFailedException: XMPPException
+{
+	OFString *operation;
+	OFString *string;
+}
+
+@property (readonly, nonatomic) OFString *operation, *string;
+
++ newWithClass: (Class)class_
+    connection: (XMPPConnection*)conn
+     operation: (OFString*)operation
+	string: (OFString*)string;
+- initWithClass: (Class)class_
+     connection: (XMPPConnection*)conn
+      operation: (OFString*)operation
+	 string: (OFString*)string;
+@end

Index: src/XMPPExceptions.m
==================================================================
--- src/XMPPExceptions.m
+++ src/XMPPExceptions.m
@@ -138,9 +138,76 @@
 	pool = [[OFAutoreleasePool alloc] init];
 	description = [[OFString alloc] initWithFormat:
 	    @"Stringprep with profile %@ failed on string '%@'!",
 	    profile, string];
 	[pool release];
+
+	return description;
+}
+@end
+
+@implementation XMPPIDNATranslationFailedException
+@synthesize operation, string;
+
++ newWithClass: (Class)class_
+    connection: (XMPPConnection*)conn
+     operation: (OFString*)operation
+	string: (OFString*)string
+{
+	return [[self alloc] initWithClass: class_
+				connection: conn
+				 operation: operation
+				    string: string];
+}
+
+- initWithClass: (Class)class_
+     connection: (XMPPConnection*)conn
+{
+	Class c = isa;
+	[self release];
+	@throw [OFNotImplementedException newWithClass: c
+					      selector: _cmd];
+}
+
+- initWithClass: (Class)class_
+     connection: (XMPPConnection*)conn
+      operation: (OFString*)operation_
+	 string: (OFString*)string_
+{
+	self = [super initWithClass: class_
+			 connection: conn];
+
+	@try {
+		operation = [operation_ copy];
+		string = [string_ copy];
+	} @catch (id e) {
+		[self release];
+		@throw e;
+	}
+
+	return self;
+}
+
+- (void)dealloc
+{
+	[operation release];
+	[string release];
+
+	[super dealloc];
+}
+
+- (OFString*)description
+{
+	OFAutoreleasePool *pool;
+
+	if (description != nil)
+		return description;
+
+	pool = [[OFAutoreleasePool alloc] init];
+	description = [[OFString alloc] initWithFormat:
+	    @"IDNA operation %@ failed on string '%@'!",
+	    operation, string];
+	[pool release];
 
 	return description;
 }
 @end