Index: src/OFMutableURL.m
==================================================================
--- src/OFMutableURL.m
+++ src/OFMutableURL.m
@@ -68,12 +68,17 @@
 - (void)setHost: (OFString *)host
 {
 	void *pool = objc_autoreleasePoolPush();
 	OFString *old = _URLEncodedHost;
 
-	_URLEncodedHost = [[host stringByURLEncodingWithAllowedCharacters:
-	    [OFCharacterSet URLHostAllowedCharacterSet]] copy];
+	if (of_url_is_ipv6_host(host))
+		_URLEncodedHost = [[OFString alloc]
+		    initWithFormat: @"[%@]", host];
+	else
+		_URLEncodedHost = [[host
+		    stringByURLEncodingWithAllowedCharacters:
+		    [OFCharacterSet URLHostAllowedCharacterSet]] copy];
 
 	[old release];
 
 	objc_autoreleasePoolPop(pool);
 }
@@ -80,11 +85,16 @@
 
 - (void)setURLEncodedHost: (OFString *)URLEncodedHost
 {
 	OFString *old;
 
-	if (URLEncodedHost != nil)
+	if ([URLEncodedHost hasPrefix: @"["] &&
+	    [URLEncodedHost hasSuffix: @"]"]) {
+		if (!of_url_is_ipv6_host([URLEncodedHost substringWithRange:
+		    of_range(1, URLEncodedHost.length - 2)]))
+			@throw [OFInvalidFormatException exception];
+	} else if (URLEncodedHost != nil)
 		of_url_verify_escaped(URLEncodedHost,
 		    [OFCharacterSet URLHostAllowedCharacterSet]);
 
 	old = _URLEncodedHost;
 	_URLEncodedHost = [URLEncodedHost copy];

Index: src/OFURL.h
==================================================================
--- src/OFURL.h
+++ src/OFURL.h
@@ -340,9 +340,17 @@
  *
  * @return The characters allowed in the fragment part of a URL.
  */
 + (OFCharacterSet *)URLFragmentAllowedCharacterSet;
 @end
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+extern bool of_url_is_ipv6_host(OFString *host);
+#ifdef __cplusplus
+}
+#endif
 
 OF_ASSUME_NONNULL_END
 
 #import "OFMutableURL.h"

Index: src/OFURL.m
==================================================================
--- src/OFURL.m
+++ src/OFURL.m
@@ -67,10 +67,31 @@
 }
 
 - (instancetype)of_initWithCharacterSet: (OFCharacterSet *)characterSet
     OF_METHOD_FAMILY(init);
 @end
+
+bool
+of_url_is_ipv6_host(OFString *host)
+{
+	const char *UTF8String = host.UTF8String;
+	bool hasColon = false;
+
+	while (*UTF8String != '\0') {
+		if (!of_ascii_isdigit(*UTF8String) && *UTF8String != ':' &&
+		    (*UTF8String < 'a' || *UTF8String > 'f') &&
+		    (*UTF8String < 'A' || *UTF8String > 'F'))
+			return false;
+
+		if (*UTF8String == ':')
+			hasColon = true;
+
+		UTF8String++;
+	}
+
+	return hasColon;
+}
 
 @implementation OFURLAllowedCharacterSetBase
 - (instancetype)init
 {
 	OF_INVALID_INIT_METHOD
@@ -829,10 +850,21 @@
 	return _URLEncodedScheme;
 }
 
 - (OFString *)host
 {
+	if ([_URLEncodedHost hasPrefix: @"["] &&
+	    [_URLEncodedHost hasSuffix: @"]"]) {
+		OFString *host = [_URLEncodedHost substringWithRange:
+		    of_range(1, _URLEncodedHost.length - 2)];
+
+		if (!of_url_is_ipv6_host(host))
+			@throw [OFInvalidArgumentException exception];
+
+		return host;
+	}
+
 	return _URLEncodedHost.stringByURLDecoding;
 }
 
 - (OFString *)URLEncodedHost
 {

Index: tests/OFURLTests.m
==================================================================
--- tests/OFURLTests.m
+++ tests/OFURLTests.m
@@ -152,12 +152,12 @@
 
 	TEST(@"-[user]", [u1.user isEqual: @"us:er"] && u4.user == nil)
 	TEST(@"-[password]",
 	    [u1.password isEqual: @"p@w"] && u4.password == nil)
 	TEST(@"-[host]", [u1.host isEqual: @"ho:st"] &&
-	    [u6.host isEqual: @"[12:34::56:abcd]"] &&
-	    [u7.host isEqual: @"[12:34::56:abcd]"])
+	    [u6.host isEqual: @"12:34::56:abcd"] &&
+	    [u7.host isEqual: @"12:34::56:abcd"])
 	TEST(@"-[port]", [u1.port isEqual: [OFNumber numberWithUInt16: 1234]] &&
 	    [u4 port] == nil &&
 	    [u7.port isEqual: [OFNumber numberWithUInt16: 234]])
 	TEST(@"-[path]",
 	    [u1.path isEqual: @"/pa?th"] && [u4.path isEqual: @"/etc/passwd"])
@@ -204,17 +204,31 @@
 	EXPECT_EXCEPTION(
 	    @"-[setURLEncodedScheme:] with invalid characters fails",
 	    OFInvalidFormatException, mu.URLEncodedScheme = @"~")
 
 	TEST(@"-[setHost:]",
-	    (mu.host = @"ho:st") && [mu.URLEncodedHost isEqual: @"ho%3Ast"])
+	    (mu.host = @"ho:st") && [mu.URLEncodedHost isEqual: @"ho%3Ast"] &&
+	    (mu.host = @"12:34:ab") &&
+	    [mu.URLEncodedHost isEqual: @"[12:34:ab]"] &&
+	    (mu.host = @"12:34:aB") &&
+	    [mu.URLEncodedHost isEqual: @"[12:34:aB]"] &&
+	    (mu.host = @"12:34:g") &&
+	    [mu.URLEncodedHost isEqual: @"12%3A34%3Ag"])
 
 	TEST(@"-[setURLEncodedHost:]",
-	    (mu.URLEncodedHost = @"ho%3Ast") && [mu.host isEqual: @"ho:st"])
+	    (mu.URLEncodedHost = @"ho%3Ast") && [mu.host isEqual: @"ho:st"] &&
+	    (mu.URLEncodedHost = @"[12:34]") && [mu.host isEqual: @"12:34"] &&
+	    (mu.URLEncodedHost = @"[12::ab]") && [mu.host isEqual: @"12::ab"])
+
+	EXPECT_EXCEPTION(@"-[setURLEncodedHost:] with invalid characters fails"
+	    " #1", OFInvalidFormatException, mu.URLEncodedHost = @"/")
+
+	EXPECT_EXCEPTION(@"-[setURLEncodedHost:] with invalid characters fails"
+	    " #2", OFInvalidFormatException, mu.URLEncodedHost = @"[12:34")
 
-	EXPECT_EXCEPTION(@"-[setURLEncodedHost:] with invalid characters fails",
-	    OFInvalidFormatException, mu.URLEncodedHost = @"/")
+	EXPECT_EXCEPTION(@"-[setURLEncodedHost:] with invalid characters fails"
+	    " #3", OFInvalidFormatException, mu.URLEncodedHost = @"[a::g]")
 
 	TEST(@"-[setUser:]",
 	    (mu.user = @"us:er") && [mu.URLEncodedUser isEqual: @"us%3Aer"])
 
 	TEST(@"-[setURLEncodedUser:]",