diff --git a/merra_vs_cfsr/merra_vs_cfsr.py b/merra_vs_cfsr/merra_vs_cfsr.py
index 14a30a33af5308acba8bbdc8f33192519c36fc72..64884c3fbdd7058a632ed73add2173ab8cdc2b3a 100644
--- a/merra_vs_cfsr/merra_vs_cfsr.py
+++ b/merra_vs_cfsr/merra_vs_cfsr.py
@@ -274,7 +274,7 @@ def populate_means(merra_file, erai_file, cfsr_file,
                         )
                 s['erai_counts'][level][mask] += 1
 
-                mask = good_mask(cfsr_data_regrid)
+                mask = good_mask(cfsr_data_2d)
                 s['cfsr_totals'][level][mask] += (
                             cfsr_data_2d[mask]
                         )