diff --git a/diagonals/regmean.py b/diagonals/regmean.py
index 8da71dc7d307ce4d186075f7bcf8d463cc11abea..efce77b9fa102a2a5aa050bcd148beb5c0e5c8c8 100644
--- a/diagonals/regmean.py
+++ b/diagonals/regmean.py
@@ -117,8 +117,8 @@ def _compute_regmean_2d_cpu(var, basins, area):
         weights = _compute_weights_2d(mask, area)
         regmean = np.empty(times)
         for t in range(times):
-            regmean[t] = np.average(var[t, :, :], axis=(0, 1),
-                                    weights=np.squeeze(weights))
+            regmean[t] = np.ma.average(
+                var[t, :, :], axis=(0, 1), weights=np.squeeze(weights))
         regmean_total[basin] = regmean
     return regmean_total
 
@@ -148,8 +148,8 @@ def _compute_regmean_3d_cpu(var, basins, volume):
         weights = _compute_weights_3d(mask, volume)
         regmean = np.empty(times)
         for t in range(times):
-            regmean[t] = np.average(var[t, :, :, :], axis=(0, 1, 2),
-                                    weights=np.squeeze(weights))
+            regmean[t] = np.ma.average(
+                var[t, :, :, :], axis=(0, 1, 2), weights=np.squeeze(weights))
         regmean_total[basin] = regmean
     return regmean_total