@@ -1404,10 +1404,26 @@
 	OFMutableString *new;
 
 	new = [OFMutableString stringWithString: self];
 	[new appendString: string_];
 
+	/*
+	 * Class swizzle the string to be immutable. We declared the return type
+	 * to be OFString*, so it can't be modified anyway. But not swizzling it
+	 * would create a real copy each time -[copy] is called.
+	 */
+	new->isa = [OFString class];
+	return new;
+}
+
+- (OFString*)stringByPrependingString: (OFString*)string_
+{
+	OFMutableString *new;
+
+	new = [OFMutableString stringWithString: string_];
+	[new appendString: self];
+
 	/*
 	 * Class swizzle the string to be immutable. We declared the return type
 	 * to be OFString*, so it can't be modified anyway. But not swizzling it
 	 * would create a real copy each time -[copy] is called.
 	 */