diff --git a/src/Tree/Mapping/Driver/Xml.php b/src/Tree/Mapping/Driver/Xml.php
index 1c1b80e527..611e8b38ac 100644
--- a/src/Tree/Mapping/Driver/Xml.php
+++ b/src/Tree/Mapping/Driver/Xml.php
@@ -108,7 +108,7 @@ public function readExtendedMetadata($meta, array &$config)
                         throw new InvalidMappingException("Tree Path field - [{$field}] Separator {$separator} is invalid. It must be only one character long.");
                     }
 
-                    $appendId = !$this->_isAttributeSet($mapping->{'tree-path'}, 'append_id') || $this->_getBooleanAttribute($mapping->{'tree-path'}, 'append_id');
+                    $appendId = $this->_isAttributeSet($mapping->{'tree-path'}, 'append_id') ? $this->_getBooleanAttribute($mapping->{'tree-path'}, 'append_id') : null;
                     $startsWithSeparator = $this->_isAttributeSet($mapping->{'tree-path'}, 'starts_with_separator') && $this->_getBooleanAttribute($mapping->{'tree-path'}, 'starts_with_separator');
                     $endsWithSeparator = !$this->_isAttributeSet($mapping->{'tree-path'}, 'ends_with_separator') || $this->_getBooleanAttribute($mapping->{'tree-path'}, 'ends_with_separator');
 
diff --git a/src/Tree/TreeListener.php b/src/Tree/TreeListener.php
index d411387a06..6c73515b5c 100644
--- a/src/Tree/TreeListener.php
+++ b/src/Tree/TreeListener.php
@@ -33,7 +33,7 @@
  *   path?: string,
  *   path_source?: string,
  *   path_separator?: string,
- *   path_append_id?: bool,
+ *   path_append_id?: ?bool,
  *   path_starts_with_separator?: bool,
  *   path_ends_with_separator?: bool,
  *   path_hash?: string,