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
@@ -447,6 +447,30 @@
     sysctl_kern_securelvl, "I",
     "Current secure level");
 
+static int
+sysctl_kern_fallback_elf_brand(SYSCTL_HANDLER_ARGS)
+{
+	struct prison *pr;
+	int error, fallback_elf_brand;
+
+	pr = req->td->td_ucred->cr_prison;
+	fallback_elf_brand = pr->pr_elf_fallback_brand;
+	error = sysctl_handle_int(oidp, &fallback_elf_brand, 0, req);
+	if (error || !req->newptr)
+		return (error);
+	sx_slock(&allprison_lock);
+	mtx_lock(&pr->pr_mtx);
+	pr->pr_elf_fallback_brand = fallback_elf_brand;
+	mtx_unlock(&pr->pr_mtx);
+	sx_sunlock(&allprison_lock);
+	return (error);
+}
+
+SYSCTL_PROC(_kern, OID_AUTO, fallback_elf_brand,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_MPSAFE, 0, 0,
+    sysctl_kern_fallback_elf_brand, "I",
+    "Current ELF ABI fallback brand");
+
 #ifdef INCLUDE_CONFIG_FILE
 /* Actual kernel configuration options. */
 extern char kernconfstring[];
@@ -736,10 +760,3 @@
 const int pcb_size = sizeof(struct pcb);
 SYSCTL_INT(_debug_sizeof, OID_AUTO, pcb, CTLFLAG_RD,
     SYSCTL_NULL_INT_PTR, sizeof(struct pcb), "sizeof(struct pcb)");
-
-/* XXX compatibility, remove for 6.0 */
-#include <sys/imgact.h>
-#include <sys/imgact_elf.h>
-SYSCTL_INT(_kern, OID_AUTO, fallback_elf_brand, CTLFLAG_RW,
-    &__elfN(fallback_brand), sizeof(__elfN(fallback_brand)),
-    "compatibility for kern.fallback_elf_brand");