diff --git a/runtime/doc/pattern.txt b/runtime/doc/pattern.txt
index 20fed55..c23fdb4 100644
--- a/runtime/doc/pattern.txt
+++ b/runtime/doc/pattern.txt
@@ -1217,7 +1217,7 @@
 
 \%d123	Matches the character specified with a decimal number.  Must be
 	followed by a non-digit.
-\%o40	Matches the character specified with an octal number up to 0377.
+\%o40	Matches the character specified with an octal number up to 0o377.
 	Numbers below 0o40 must be followed by a non-octal digit or a
 	non-digit.
 \%x2a	Matches the character specified with up to two hexadecimal characters.