diff --git a/pymaster/field.py b/pymaster/field.py
index a2b1b34..3d502ad 100644
--- a/pymaster/field.py
+++ b/pymaster/field.py
@@ -1014,6 +1014,9 @@ def __init__(self, positions, weights, positions_rand, weights_rand,
         self.alm_temp = None
         self.minfo = None
         self.n_temp = 0
+        self.anisotropic_mask = False
+        self.mask_a = None
+        self.alm_mask_a = None
 
         # Sanity checks on positions and weights
         def process_pos_w(pos, w, kind):