Fixed a typo in the attribute name (Thanks ingy).
diff --git a/lib/yaml/serializer.py b/lib/yaml/serializer.py
index 2101f95..0bf1e96 100644
--- a/lib/yaml/serializer.py
+++ b/lib/yaml/serializer.py
@@ -55,7 +55,7 @@
         self.emit(DocumentEndEvent(explicit=self.use_explicit_end))
         self.serialized_nodes = {}
         self.anchors = {}
-        self.last_alias_id = 0
+        self.last_anchor_id = 0
 
     def anchor_node(self, node):
         if node in self.anchors:
diff --git a/lib3/yaml/serializer.py b/lib3/yaml/serializer.py
index 7daf0e7..fe911e6 100644
--- a/lib3/yaml/serializer.py
+++ b/lib3/yaml/serializer.py
@@ -55,7 +55,7 @@
         self.emit(DocumentEndEvent(explicit=self.use_explicit_end))
         self.serialized_nodes = {}
         self.anchors = {}
-        self.last_alias_id = 0
+        self.last_anchor_id = 0
 
     def anchor_node(self, node):
         if node in self.anchors: