diff --git a/sys/arm64/arm64/elf32_machdep.c b/sys/arm64/arm64/elf32_machdep.c
--- a/sys/arm64/arm64/elf32_machdep.c
+++ b/sys/arm64/arm64/elf32_machdep.c
@@ -160,6 +160,8 @@
 	if (ID_AA64PFR0_EL0_VAL(READ_SPECIALREG(id_aa64pfr0_el1)) ==
 	    ID_AA64PFR0_EL0_64_32) {
 		elf32_insert_brand_entry(&freebsd32_brand_info);
+	} else {
+		compat_freebsd_32bit = 0;
 	}
 }
 SYSINIT(elf32, SI_SUB_EXEC, SI_ORDER_FIRST, register_elf32_brand, NULL);
diff --git a/sys/compat/freebsd32/freebsd32_misc.c b/sys/compat/freebsd32/freebsd32_misc.c
--- a/sys/compat/freebsd32/freebsd32_misc.c
+++ b/sys/compat/freebsd32/freebsd32_misc.c
@@ -123,7 +123,9 @@
 #include <compat/freebsd32/freebsd32_signal.h>
 #include <compat/freebsd32/freebsd32_proto.h>
 
-FEATURE(compat_freebsd_32bit, "Compatible with 32-bit FreeBSD");
+int compat_freebsd_32bit = 1;
+FEATURE_DYN(compat_freebsd_32bit, compat_freebsd_32bit,
+    "Compatible with 32-bit FreeBSD");
 
 struct ptrace_io_desc32 {
 	int		piod_op;
diff --git a/sys/compat/freebsd32/freebsd32_util.h b/sys/compat/freebsd32/freebsd32_util.h
--- a/sys/compat/freebsd32/freebsd32_util.h
+++ b/sys/compat/freebsd32/freebsd32_util.h
@@ -122,4 +122,6 @@
 int freebsd32_exec_copyin_args(struct image_args *args, const char *fname,
 	    enum uio_seg segflg, uint32_t *argv, uint32_t *envv);
 
+extern int compat_freebsd_32bit;
+
 #endif /* !_COMPAT_FREEBSD32_FREEBSD32_UTIL_H_ */
diff --git a/sys/kern/kern_mib.c b/sys/kern/kern_mib.c
--- a/sys/kern/kern_mib.c
+++ b/sys/kern/kern_mib.c
@@ -316,16 +316,25 @@
     CTLFLAG_CAPRD | CTLFLAG_MPSAFE, NULL, 0, sysctl_hw_machine_arch, "A",
     "System architecture");
 
-#ifndef MACHINE_ARCHES
 #ifdef COMPAT_FREEBSD32
-#define	MACHINE_ARCHES	MACHINE_ARCH " " MACHINE_ARCH32
-#else
-#define	MACHINE_ARCHES	MACHINE_ARCH
-#endif
+#include <compat/freebsd32/freebsd32_util.h>
 #endif
 
-SYSCTL_STRING(_kern, OID_AUTO, supported_archs, CTLFLAG_RD | CTLFLAG_MPSAFE,
-    MACHINE_ARCHES, 0, "Supported architectures for binaries");
+static int
+sysctl_kern_supported_archs(SYSCTL_HANDLER_ARGS)
+{
+	const char *supported_archs;
+
+	supported_archs =
+#ifdef COMPAT_FREEBSD32
+	    compat_freebsd_32bit ? MACHINE_ARCH " " MACHINE_ARCH32 :
+#endif
+	    MACHINE_ARCH;
+	return (SYSCTL_OUT(req, supported_archs, strlen(supported_archs) + 1));
+}
+SYSCTL_PROC(_kern, OID_AUTO, supported_archs, CTLFLAG_RD | CTLFLAG_MPSAFE |
+    CTLFLAG_CAPRD | CTLTYPE_STRING, NULL, 0, sysctl_kern_supported_archs, "A",
+    "Supported architectures for binaries");
 
 static int
 sysctl_hostname(SYSCTL_HANDLER_ARGS)
diff --git a/sys/sys/sysctl.h b/sys/sys/sysctl.h
--- a/sys/sys/sysctl.h
+++ b/sys/sys/sysctl.h
@@ -927,6 +927,9 @@
 #define	FEATURE(name, desc)						\
 	SYSCTL_INT_WITH_LABEL(_kern_features, OID_AUTO, name,		\
 	    CTLFLAG_RD | CTLFLAG_CAPRD, SYSCTL_NULL_INT_PTR, 1, desc, "feature")
+#define	FEATURE_DYN(name, ptr, desc)					\
+	SYSCTL_INT_WITH_LABEL(_kern_features, OID_AUTO, name,		\
+	    CTLFLAG_RD | CTLFLAG_CAPRD, &ptr, 0, desc, "feature")
 
 #endif /* _KERNEL */