@@ -21,10 +21,11 @@
 #include <assert.h>
 
 #import "OFDictionary.h"
 #import "OFDictionary_hashtable.h"
 #import "OFArray.h"
+#import "OFCharacterSet.h"
 #import "OFString.h"
 #import "OFXMLElement.h"
 #import "OFData.h"
 
 #import "OFInvalidArgumentException.h"
@@ -33,17 +34,23 @@
 
 static struct {
 	Class isa;
 } placeholder;
 
+static OFCharacterSet *URLQueryPartAllowedCharacterSet = nil;
+
 @interface OFDictionary ()
 - (OFString *)of_JSONRepresentationWithOptions: (int)options
 					 depth: (size_t)depth;
 @end
 
 @interface OFDictionary_placeholder: OFDictionary
 @end
+
+@interface OFCharacterSet_URLQueryPartAllowed: OFCharacterSet
++ (OFCharacterSet *)URLQueryPartAllowedCharacterSet;
+@end
 
 @implementation OFDictionary_placeholder
 - (instancetype)init
 {
 	return (id)[[OFDictionary_hashtable alloc] init];
@@ -119,10 +126,70 @@
 }
 
 - (void)dealloc
 {
 	OF_DEALLOC_UNSUPPORTED
+}
+@end
+
+@implementation OFCharacterSet_URLQueryPartAllowed
++ (void)initialize
+{
+	if (self != [OFCharacterSet_URLQueryPartAllowed class])
+		return;
+
+	URLQueryPartAllowedCharacterSet =
+	    [[OFCharacterSet_URLQueryPartAllowed alloc] init];
+}
+
++ (OFCharacterSet *)URLQueryPartAllowedCharacterSet
+{
+	return URLQueryPartAllowedCharacterSet;
+}
+
+- (instancetype)autorelease
+{
+	return self;
+}
+
+- (instancetype)retain
+{
+	return self;
+}
+
+- (void)release
+{
+}
+
+- (unsigned int)retainCount
+{
+	return OF_RETAIN_COUNT_MAX;
+}
+
+- (bool)characterIsMember: (of_unichar_t)character
+{
+	if (character < CHAR_MAX && of_ascii_isalnum(character))
+		return true;
+
+	switch (character) {
+	case '-':
+	case '.':
+	case '_':
+	case '~':
+	case '!':
+	case '$':
+	case '\'':
+	case '(':
+	case ')':
+	case '*':
+	case '+':
+	case ',':
+	case ';':
+		return true;
+	default:
+		return false;
+	}
 }
 @end
 
 @implementation OFDictionary
 + (void)initialize
@@ -574,10 +641,12 @@
 {
 	OFMutableString *ret = [OFMutableString string];
 	void *pool = objc_autoreleasePoolPush();
 	OFEnumerator *keyEnumerator = [self keyEnumerator];
 	OFEnumerator *objectEnumerator = [self objectEnumerator];
+	OFCharacterSet *allowed = [OFCharacterSet_URLQueryPartAllowed
+	    URLQueryPartAllowedCharacterSet];
 	bool first = true;
 	id key, object;
 
 	while ((key = [keyEnumerator nextObject]) != nil &&
 	    (object = [objectEnumerator nextObject]) != nil) {
@@ -585,14 +654,14 @@
 			first = false;
 		else
 			[ret appendString: @"&"];
 
 		[ret appendString: [[key description]
-		    stringByURLEncodingWithAllowedCharacters: "-._~!$'()*+,;"]];
+		    stringByURLEncodingWithAllowedCharacters: allowed]];
 		[ret appendString: @"="];
 		[ret appendString: [[object description]
-		    stringByURLEncodingWithAllowedCharacters: "-._~!$'()*+,;"]];
+		    stringByURLEncodingWithAllowedCharacters: allowed]];
 	}
 
 	[ret makeImmutable];
 
 	objc_autoreleasePoolPop(pool);