diff --git a/lib/libc/string/strchr.3 b/lib/libc/string/strchr.3
index 6117831233a..a39ea3e79d7 100644
--- a/lib/libc/string/strchr.3
+++ b/lib/libc/string/strchr.3
@@ -113,10 +113,12 @@ and
 .Fn strrchr
 conform to
 .St -isoC .
-The
+The function
 .Fn strchrnul
-is a GNU extension .
-.Sh History
+is a
+.Tn GNU
+extension.
+.Sh HISTORY
 The
 .Fn strchrnul
 function first appeared in glibc 2.1.1 and was added in