diff --git a/doc/src/lattice.rst b/doc/src/lattice.rst
index 277f648515..3306c58e8c 100644
--- a/doc/src/lattice.rst
+++ b/doc/src/lattice.rst
@@ -129,12 +129,13 @@ and a3 are 3 orthogonal unit vectors (edges of a unit cube).  But you
 can specify them to be of any length and non-orthogonal to each other,
 so that they describe a tilted parallelepiped.  Via the *basis*
 keyword you add atoms, one at a time, to the unit cell.  Its arguments
-are fractional coordinates (0.0 <= x,y,z < 1.0).  The position vector
-x of a basis atom within the unit cell is thus a linear combination of
-the unit cell's 3 edge vectors, i.e. x = bx a1 + by a2 + bz a3, where
-bx,by,bz are the 3 values specified for the *basis* keyword.  For 2d
-simulations, the fractional z coordinate for any basis atom must be
-0.0.
+are fractional coordinates (0.0 <= x,y,z < 1.0).  For 2d simulations,
+the fractional z coordinate for any basis atom must be 0.0.
+
+The position vector x of a basis atom within the unit cell is a linear
+combination of the unit cell's 3 edge vectors, i.e. x = bx a1 + by
+a2 + bz a3, where bx,by,bz are the 3 values specified for the *basis*
+keyword.
 
 ----------