diff --git a/lib/libio/alpha_sethae.c b/lib/libio/alpha_sethae.c
index d7bdaa82ea72..00b23d0eb3db 100644
--- a/lib/libio/alpha_sethae.c
+++ b/lib/libio/alpha_sethae.c
@@ -24,10 +24,9 @@
  * SUCH DAMAGE.
  */
 
-#if defined(LIBC_RCS) && !defined(lint)
-static const char rcsid[] =
-  "$FreeBSD$";
-#endif /* LIBC_RCS and not lint */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 #include <machine/sysarch.h>
diff --git a/lib/libio/bwx.c b/lib/libio/bwx.c
index f923572e1072..5b479686f376 100644
--- a/lib/libio/bwx.c
+++ b/lib/libio/bwx.c
@@ -22,10 +22,11 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
  */
 
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
 #include <sys/param.h>
 #include <sys/mman.h>
 #include <sys/fcntl.h>
diff --git a/lib/libio/io.c b/lib/libio/io.c
index 3ccce2e4b32a..a963349f29e1 100644
--- a/lib/libio/io.c
+++ b/lib/libio/io.c
@@ -22,10 +22,11 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
  */
 
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
 #include <sys/types.h>
 #include <sys/sysctl.h>
 #include <err.h>
diff --git a/lib/libio/swiz.c b/lib/libio/swiz.c
index b30dfa3f3b00..eab2a0380b63 100644
--- a/lib/libio/swiz.c
+++ b/lib/libio/swiz.c
@@ -22,10 +22,11 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
  */
 
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
 #include <sys/param.h>
 #include <sys/mman.h>
 #include <sys/fcntl.h>