diff --git a/source/lex.tex b/source/lex.tex
index ed45edd697..99d595af28 100644
--- a/source/lex.tex
+++ b/source/lex.tex
@@ -139,6 +139,7 @@
 except when matching a
 \grammarterm{c-char-sequence},
 \grammarterm{s-char-sequence},
+\grammarterm{d-char-sequence},
 \grammarterm{r-char-sequence},
 \grammarterm{h-char-sequence}, or
 \grammarterm{q-char-sequence},