Index: src/OFURL.h
==================================================================
--- src/OFURL.h
+++ src/OFURL.h
@@ -238,10 +238,36 @@
  * @return An Initialized OFURL
  */
 - (instancetype)initFileURLWithPath: (OFString *)path
 			isDirectory: (bool)isDirectory;
 #endif
+
+/*!
+ * @brief Returns a new URL with the specified path component appended.
+ *
+ * If the URL is a file URL, the file system is queried whether the appended
+ * component is a directory.
+ *
+ * @param component The path component to append. If it starts with the slash,
+ *		    the component is not appended, but replaces the path
+ *		    instead.
+ * @return A new URL with the specified path component appended
+ */
+- (OFURL *)URLByAppendingPathComponent: (OFString *)component;
+
+/*!
+ * @brief Returns a new URL with the specified path component appended.
+ *
+ * @param component The path component to append. If it starts with the slash,
+ *		    the component is not appended, but replaces the path
+ *		    instead.
+ * @param isDirectory Whether the appended component is a directory, meaning
+ *		      that the URL path should have a trailing slash
+ * @return A new URL with the specified path component appended
+ */
+- (OFURL *)URLByAppendingPathComponent: (OFString *)component
+			   isDirectory: (bool)isDirectory;
 @end
 
 @interface OFCharacterSet (URLCharacterSets)
 #ifdef OF_HAVE_CLASS_PROPERTIES
 @property (class, readonly, nonatomic)

Index: src/OFURL.m
==================================================================
--- src/OFURL.m
+++ src/OFURL.m
@@ -993,10 +993,78 @@
 
 	objc_autoreleasePoolPop(pool);
 
 	return [path autorelease];
 }
+
+- (OFMutableURL *)of_URLByAppendingPathComponent: (OFString *)component
+{
+	OFMutableURL *ret = [[self mutableCopy] autorelease];
+	void *pool;
+	OFMutableString *URLEncodedPath;
+
+	if ([component hasPrefix: @"/"]) {
+		[ret setPath: component];
+		return ret;
+	}
+
+	pool = objc_autoreleasePoolPush();
+	URLEncodedPath = [[[self URLEncodedPath] mutableCopy] autorelease];
+
+	if (![URLEncodedPath hasSuffix: @"/"])
+		[URLEncodedPath appendString: @"/"];
+
+	[URLEncodedPath appendString:
+	    [component stringByURLEncodingWithAllowedCharacters:
+	    [OFCharacterSet URLPathAllowedCharacterSet]]];
+
+	[ret setURLEncodedPath: URLEncodedPath];
+
+	objc_autoreleasePoolPop(pool);
+
+	return ret;
+}
+
+- (OFURL *)URLByAppendingPathComponent: (OFString *)component
+{
+	OFMutableURL *ret = [self of_URLByAppendingPathComponent: component];
+
+#ifdef OF_HAVE_FILES
+	if ([[ret scheme] isEqual: @"file"]) {
+		void *pool = objc_autoreleasePoolPush();
+
+		if ([[OFFileManager defaultManager] directoryExistsAtURL: ret])
+			[ret setURLEncodedPath: [[ret URLEncodedPath]
+			    stringByAppendingString: @"/"]];
+
+		objc_autoreleasePoolPop(pool);
+	}
+#endif
+
+	[ret makeImmutable];
+
+	return ret;
+}
+
+- (OFURL *)URLByAppendingPathComponent: (OFString *)component
+			   isDirectory: (bool)isDirectory
+{
+	OFMutableURL *ret = [self of_URLByAppendingPathComponent: component];
+
+	if (isDirectory) {
+		void *pool = objc_autoreleasePoolPush();
+
+		[ret setURLEncodedPath:
+		    [[ret URLEncodedPath] stringByAppendingString: @"/"]];
+
+		objc_autoreleasePoolPop(pool);
+	}
+
+	[ret makeImmutable];
+
+	return ret;
+}
 
 - (OFString *)description
 {
 	return [OFString stringWithFormat: @"<%@: %@>",
 					   [self class], [self string]];

Index: tests/OFURLTests.m
==================================================================
--- tests/OFURLTests.m
+++ tests/OFURLTests.m
@@ -236,9 +236,39 @@
 	    [[mu fragment] isEqual: @"frag/ment?#"])
 
 	EXPECT_EXCEPTION(
 	    @"-[setURLEncodedFragment:] with invalid characters fails",
 	    OFInvalidFormatException, [mu setURLEncodedFragment: @"`"])
+
+	TEST(@"-[URLByAppendingPathComponent:isDirectory:]",
+	    [[[OFURL URLWithString: @"file:///foo/bar"]
+	    URLByAppendingPathComponent: @"qux"
+			    isDirectory: false] isEqual:
+	    [OFURL URLWithString: @"file:///foo/bar/qux"]] &&
+	    [[[OFURL URLWithString: @"file:///foo/bar/"]
+	    URLByAppendingPathComponent: @"qux"
+			    isDirectory: false] isEqual:
+	    [OFURL URLWithString: @"file:///foo/bar/qux"]] &&
+	    [[[OFURL URLWithString: @"file:///foo/bar/"]
+	    URLByAppendingPathComponent: @"qu?x"
+			    isDirectory: false] isEqual:
+	    [OFURL URLWithString: @"file:///foo/bar/qu%3Fx"]] &&
+	    [[[OFURL URLWithString: @"file:///foo/bar/"]
+	    URLByAppendingPathComponent: @"qu?x"
+			    isDirectory: true] isEqual:
+	    [OFURL URLWithString: @"file:///foo/bar/qu%3Fx/"]] &&
+	    [[[OFURL URLWithString: @"file:///foo/bar/"]
+	    URLByAppendingPathComponent: @"/qux"
+			    isDirectory: false] isEqual:
+	    [OFURL URLWithString: @"file:///qux"]] &&
+	    [[[OFURL URLWithString: @"file:///foo/bar/"]
+	    URLByAppendingPathComponent: @"/qu?x"
+			    isDirectory: false] isEqual:
+	    [OFURL URLWithString: @"file:///qu%3Fx"]] &&
+	    [[[OFURL URLWithString: @"file:///foo/bar/"]
+	    URLByAppendingPathComponent: @"/qu?x"
+			    isDirectory: true] isEqual:
+	    [OFURL URLWithString: @"file:///qu%3Fx/"]])
 
 	[pool drain];
 }
 @end