diff --git a/BUGS.rst b/BUGS.rst
index 8c8508b..93eb87a 100644
--- a/BUGS.rst
+++ b/BUGS.rst
@@ -1,6 +1,13 @@
 Known bugs
 ===========
 
+Wrong factor on B coefficient
+-----------------------------
+Under Kristensson normalisation (with CS = -1), my code gives
+B(1,0,n,n)/B(1,0,n,-n) == -(2n)! at (x,y,z) = (x,0,0)
+(expected plus or minus 1).
+A-coefficients seem to behave correctly.
+
 Scattering result asymmetry
 ---------------------------
 The lattice scattering code (such as finitesqlatzsym-scattery.py) produces