diff --git a/validphys2/src/validphys/process_options.py b/validphys2/src/validphys/process_options.py
index e7e44a1bc9c86bad6205e3c2df7c8e5675724ffe..73435ea92e69bb6e4bd0b4f83a0e62cb38da0a70 100644
--- a/validphys2/src/validphys/process_options.py
+++ b/validphys2/src/validphys/process_options.py
@@ -32,7 +32,6 @@ class _Vars:
     m_ttBar = "m_ttBar"
     eta = "eta"
     m_W2 = "m_W2"
-    extra_0 = "extra_0"
 
 
 class _KinematicsInformation: