diff --git a/Sources/HTMLElement.m b/Sources/HTMLElement.m
index 7904e33..2686818 100644
--- a/Sources/HTMLElement.m
+++ b/Sources/HTMLElement.m
@@ -144,7 +144,7 @@
 {
 	HTMLElement *copy = [super copyWithZone:zone];
 	copy->_tagName = [_tagName copy];
-	copy->_attributes = [_attributes copy];
+	copy->_attributes = [_attributes mutableCopy];
 	copy->_htmlNamespace = _htmlNamespace;
 	return copy;
 }
diff --git a/Tests/HTMLKitTests/HTMLNodesTests.m b/Tests/HTMLKitTests/HTMLNodesTests.m
index 8e994dd..7b627cf 100644
--- a/Tests/HTMLKitTests/HTMLNodesTests.m
+++ b/Tests/HTMLKitTests/HTMLNodesTests.m
@@ -512,4 +512,15 @@
 	XCTAssertTrue([image compareDocumentPositionWithNode:outerDiv] == (HTMLDocumentPositionContainedBy | HTMLDocumentPositionFollowing));
 }
 
+- (void)testDeepCloneElement {
+    HTMLElement *element = [HTMLElement new];
+    element.elementId = @"originalId";
+    
+    HTMLElement *clone = [element cloneNodeDeep:YES];
+    NSString *cloneId = @"cloneId";
+    clone.elementId = cloneId;
+    
+    XCTAssertTrue([clone.elementId isEqualToString:cloneId]);
+}
+
 @end