Index: src/OFXMLElement.m
==================================================================
--- src/OFXMLElement.m
+++ src/OFXMLElement.m
@@ -379,11 +379,11 @@
 }
 
 - (void)setChildren: (OFArray *)children
 {
 	OFArray *old = _children;
-	_children = [children copy];
+	_children = [children mutableCopy];
 	[old release];
 }
 
 - (OFArray *)children
 {