diff --git a/share/man/man7/arch.7 b/share/man/man7/arch.7
--- a/share/man/man7/arch.7
+++ b/share/man/man7/arch.7
@@ -24,7 +24,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd October 1, 2025
+.Dd November 18, 2025
 .Dt ARCH 7
 .Os
 .Sh NAME
@@ -48,7 +48,8 @@
 .Fx
 uses a flat address space.
 Variables of types
-.Vt unsigned long
+.Vt unsigned long ,
+.Vt ptraddr_t ,
 and
 .Vt size_t
 have the same representation.
diff --git a/sys/sys/_types.h b/sys/sys/_types.h
--- a/sys/sys/_types.h
+++ b/sys/sys/_types.h
@@ -103,6 +103,12 @@
 #error unsupported ptrdiff_t size
 #endif
 
+#ifdef __PTRADDR_TYPE__
+typedef	__PTRADDR_TYPE__	__ptraddr_t;
+#else
+typedef	__size_t		__ptraddr_t;
+#endif
+
 /*
  * Target-dependent type definitions.
  */
diff --git a/sys/sys/stddef.h b/sys/sys/stddef.h
--- a/sys/sys/stddef.h
+++ b/sys/sys/stddef.h
@@ -32,6 +32,14 @@
 #include <sys/cdefs.h>
 #include <sys/_null.h>
 #include <sys/_types.h>
+#include <sys/_visible.h>
+
+#if __BSD_VISIBLE
+#ifndef _PTRADDR_T_DECLARED
+typedef	__ptraddr_t	ptraddr_t;
+#define	_PTRADDR_T_DECLARED
+#endif
+#endif
 
 #ifndef _PTRDIFF_T_DECLARED
 typedef	__ptrdiff_t	ptrdiff_t;