diff --git a/doc/prop.xml b/doc/prop.xml
index bc226d51e..e05ccec12 100644
--- a/doc/prop.xml
+++ b/doc/prop.xml
@@ -1312,7 +1312,8 @@ true
in which the lattice digraphs representing M3 and N5 are
not embeddable as lattices
(see https://en.wikipedia.org/wiki/Distributive_lattice and
- ).
+ ).
&MUTABLE_RECOMPUTED_PROP;