diff --git a/lib/libc/string/ffs.3 b/lib/libc/string/ffs.3
--- a/lib/libc/string/ffs.3
+++ b/lib/libc/string/ffs.3
@@ -27,7 +27,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd October 17, 2015
+.Dd October 25, 2025
 .Dt FFS 3
 .Os
 .Sh NAME
@@ -80,6 +80,17 @@
 .Sh SEE ALSO
 .Xr bitstring 3 ,
 .Xr bitset 9
+.Sh STANDARDS
+The
+.Fn ffs
+function conforms to
+.St -p1003.1-2008 .
+The
+.Fn ffsl
+and
+.Fn ffsll
+functions conform to
+.St -p1003.1-2024 .
 .Sh HISTORY
 The
 .Fn ffs