diff --git a/source/lex.tex b/source/lex.tex
index a26a086d5c..1ced646a79 100644
--- a/source/lex.tex
+++ b/source/lex.tex
@@ -108,10 +108,11 @@
 physical source lines to form logical source lines. Only the last
 backslash on any physical source line shall be eligible for being part
 of such a splice.
-Except for splices reverted in a raw string literal, if a splice results in
-a character sequence that matches the
-syntax of a \grammarterm{universal-character-name}, the behavior is
-undefined. A source file that is not empty and that does not end in a new-line
+\begin{note}
+Line splicing can form
+a \grammarterm{universal-character-name}\iref{lex.charset}.
+\end{note}
+A source file that is not empty and that does not end in a new-line
 character, or that ends in a splice,
 shall be processed as if an additional new-line character were appended
 to the file.
@@ -488,7 +489,7 @@
 operators and punctuators, and single non-whitespace characters that do not lexically
 match the other preprocessing token categories.
 If a \unicode{0027}{apostrophe} or a \unicode{0022}{quotation mark} character
-matches the last category, the behavior is undefined.
+matches the last category, the program is ill-formed.
 If any character not in the basic character set matches the last category,
 the program is ill-formed.
 Preprocessing tokens can be separated by
diff --git a/source/preprocessor.tex b/source/preprocessor.tex
index 0093ee7c8f..828b2c9673 100644
--- a/source/preprocessor.tex
+++ b/source/preprocessor.tex
@@ -1374,11 +1374,9 @@
 of two placemarkers results in a single placemarker preprocessing token, and
 concatenation of a placemarker with a non-placemarker preprocessing token results
 in the non-placemarker preprocessing token.
-If the result begins with a sequence matching the syntax of \grammarterm{universal-character-name},
-the behavior is undefined.
 \begin{note}
-This determination does not consider the replacement of
-\grammarterm{universal-character-name}s in translation phase 3\iref{lex.phases}.
+Concatenation can form
+a \grammarterm{universal-character-name}\iref{lex.charset}.
 \end{note}
 If the result is not a valid preprocessing token,
 the behavior is undefined.