diff --git a/source/preprocessor.tex b/source/preprocessor.tex
index b9809ae664..f1ff8d2e8c 100644
--- a/source/preprocessor.tex
+++ b/source/preprocessor.tex
@@ -1606,7 +1606,7 @@
 The replaced sequence of preprocessing tokens is terminated by the matching
 \tcode{)}
 preprocessing token, skipping intervening matched pairs of left and
-right parenthesis preprocessing tokens.
+right parentheses preprocessing tokens.
 Within the sequence of preprocessing tokens making up an invocation
 of a function-like macro,
 new-line is considered a normal whitespace character.