diff --git a/validphys2/src/validphys/cuts/filters.yaml b/validphys2/src/validphys/cuts/filters.yaml
index a95d50d7a3..4e0df53d8f 100644
--- a/validphys2/src/validphys/cuts/filters.yaml
+++ b/validphys2/src/validphys/cuts/filters.yaml
@@ -261,7 +261,7 @@
 - dataset: ATLAS_Z0_8TEV_LOWMASS_M-Y
   reason: Avoid overlap with the high mass ATLAS2DDY8TEV dataset.
   local_variables:
-    M: sqrt(M2)
+    M: sqrt(m_Z2)
     max_M: 116.0
   rule: M <= max_M