diff --git a/python/psi-api/src/com/jetbrains/python/PyNames.java b/python/psi-api/src/com/jetbrains/python/PyNames.java
index f70a06c33ef1..7f543920beb9 100644
--- a/python/psi-api/src/com/jetbrains/python/PyNames.java
+++ b/python/psi-api/src/com/jetbrains/python/PyNames.java
@@ -122,6 +122,7 @@ public class PyNames {
   public static final String SET = "set";
 
   public static final String KEYS = "keys";
+  public static final String EXTEND = "extend";
 
   public static final String PASS = "pass";