diff --git a/lib/libc/stdlib/strtonum.3 b/lib/libc/stdlib/strtonum.3
index 9c045bef42a..5be86d79886 100644
--- a/lib/libc/stdlib/strtonum.3
+++ b/lib/libc/stdlib/strtonum.3
@@ -140,7 +140,8 @@ The string did not consist solely of digit characters.
 .Sh STANDARDS
 .Fn strtonum
 is a
-.Bx extension.
+.Bx
+extension.
 The existing alternatives, such as
 .Xr atoi 3
 and