diff --git a/nbodykit/algorithms/convpower.py b/nbodykit/algorithms/convpower.py
index f284e731c..889838615 100644
--- a/nbodykit/algorithms/convpower.py
+++ b/nbodykit/algorithms/convpower.py
@@ -19,7 +19,7 @@ def get_real_Ylm(l, m):
     l : int
         the degree of the harmonic
     m : int
-        the order of the harmonic; abs(m) < l
+        the order of the harmonic; abs(m) <= l
 
     Returns
     -------
diff --git a/nbodykit/meshtools.py b/nbodykit/meshtools.py
index 51642321a..389072a8a 100644
--- a/nbodykit/meshtools.py
+++ b/nbodykit/meshtools.py
@@ -139,7 +139,12 @@ def mu(self, los):
     def nonsingular(self):
         """
         The indices on the slab of the positive frequencies
-        along the dimension specified by `symmetry_axis`
+        along the dimension specified by `symmetry_axis`.
+
+        This takes advantage of the fact that :class:`pmesh.pm.ComplexField`
+        shifts the Nyquist frequencies to the negative halves.
+        Therefore this ensures that the zero and Nyquist planes perpendicular
+        to the symmetry axis have weight 1, whereas other modes have weight 2.
 
         Returns
         -------