diff --git a/sys/arm64/arm64/db_trace.c b/sys/arm64/arm64/db_trace.c
--- a/sys/arm64/arm64/db_trace.c
+++ b/sys/arm64/arm64/db_trace.c
@@ -109,7 +109,7 @@
 
 		frame.sp = (uintptr_t)ctx->pcb_sp;
 		frame.fp = (uintptr_t)ctx->pcb_x[29];
-		frame.pc = (uintptr_t)ctx->pcb_x[30];
+		frame.pc = (uintptr_t)ctx->pcb_lr;
 		db_stack_trace_cmd(thr, &frame);
 	} else
 		db_trace_self();
diff --git a/sys/arm64/arm64/exception.S b/sys/arm64/arm64/exception.S
--- a/sys/arm64/arm64/exception.S
+++ b/sys/arm64/arm64/exception.S
@@ -39,7 +39,7 @@
 	sub	sp, sp, #128
 .endif
 	sub	sp, sp, #(TF_SIZE + 16)
-	stp	x29, x30, [sp, #(TF_SIZE)]
+	stp	x29, lr, [sp, #(TF_SIZE)]
 	stp	x28, x29, [sp, #(TF_X + 28 * 8)]
 	stp	x26, x27, [sp, #(TF_X + 26 * 8)]
 	stp	x24, x25, [sp, #(TF_X + 24 * 8)]
diff --git a/sys/arm64/arm64/genassym.c b/sys/arm64/arm64/genassym.c
--- a/sys/arm64/arm64/genassym.c
+++ b/sys/arm64/arm64/genassym.c
@@ -60,6 +60,7 @@
 ASSYM(PCB_SIZE, roundup2(sizeof(struct pcb), STACKALIGNBYTES + 1));
 ASSYM(PCB_SINGLE_STEP_SHIFT, PCB_SINGLE_STEP_SHIFT);
 ASSYM(PCB_REGS, offsetof(struct pcb, pcb_x));
+ASSYM(PCB_LR, offsetof(struct pcb, pcb_lr));
 ASSYM(PCB_SP, offsetof(struct pcb, pcb_sp));
 ASSYM(PCB_TPIDRRO, offsetof(struct pcb, pcb_tpidrro_el0));
 ASSYM(PCB_ONFAULT, offsetof(struct pcb, pcb_onfault));
diff --git a/sys/arm64/arm64/machdep.c b/sys/arm64/arm64/machdep.c
--- a/sys/arm64/arm64/machdep.c
+++ b/sys/arm64/arm64/machdep.c
@@ -732,11 +732,11 @@
 {
 	int i;
 
-	for (i = 0; i < PCB_LR; i++)
+	for (i = 0; i < nitems(pcb->pcb_x); i++)
 		pcb->pcb_x[i] = tf->tf_x[i];
 
-	pcb->pcb_x[PCB_LR] = tf->tf_lr;
-	pcb->pcb_pc = tf->tf_elr;
+	/* NB: pcb_lr is the PC, see PC_REGS() in db_machdep.h */
+	pcb->pcb_lr = tf->tf_elr;
 	pcb->pcb_sp = tf->tf_sp;
 }
 
diff --git a/sys/arm64/arm64/stack_machdep.c b/sys/arm64/arm64/stack_machdep.c
--- a/sys/arm64/arm64/stack_machdep.c
+++ b/sys/arm64/arm64/stack_machdep.c
@@ -71,7 +71,7 @@
 
 	frame.sp = td->td_pcb->pcb_sp;
 	frame.fp = td->td_pcb->pcb_x[29];
-	frame.pc = td->td_pcb->pcb_x[30];
+	frame.pc = td->td_pcb->pcb_lr;
 
 	stack_capture(td, st, &frame);
 	return (0);
diff --git a/sys/arm64/arm64/swtch.S b/sys/arm64/arm64/swtch.S
--- a/sys/arm64/arm64/swtch.S
+++ b/sys/arm64/arm64/swtch.S
@@ -101,7 +101,7 @@
 	ldp	x24, x25, [x4, #PCB_REGS + 24 * 8]
 	ldp	x26, x27, [x4, #PCB_REGS + 26 * 8]
 	ldp	x28, x29, [x4, #PCB_REGS + 28 * 8]
-	ldr	x30, [x4, #PCB_REGS + 30 * 8]
+	ldr	lr, [x4, #PCB_LR]
 
 	ret
 END(cpu_throw)
@@ -132,7 +132,7 @@
 	stp	x24, x25, [x4, #PCB_REGS + 24 * 8]
 	stp	x26, x27, [x4, #PCB_REGS + 26 * 8]
 	stp	x28, x29, [x4, #PCB_REGS + 28 * 8]
-	str	x30, [x4, #PCB_REGS + 30 * 8]
+	str	lr, [x4, #PCB_LR]
 	/* And the old stack pointer */
 	mov	x5, sp
 	mrs	x6, tpidrro_el0
@@ -198,7 +198,7 @@
 	ldp	x24, x25, [x4, #PCB_REGS + 24 * 8]
 	ldp	x26, x27, [x4, #PCB_REGS + 26 * 8]
 	ldp	x28, x29, [x4, #PCB_REGS + 28 * 8]
-	ldr	x30, [x4, #PCB_REGS + 30 * 8]
+	ldr	lr, [x4, #PCB_LR]
 
 	str	xzr, [x4, #PCB_REGS + 18 * 8]
 	ret
@@ -270,7 +270,7 @@
 	stp	x24, x25, [x0, #PCB_REGS + 24 * 8]
 	stp	x26, x27, [x0, #PCB_REGS + 26 * 8]
 	stp	x28, x29, [x0, #PCB_REGS + 28 * 8]
-	str	x30, [x0, #PCB_REGS + 30 * 8]
+	str	lr, [x0, #PCB_LR]
 	/* And the old stack pointer */
 	mov	x5, sp
 	mrs	x6, tpidrro_el0
diff --git a/sys/arm64/arm64/vm_machdep.c b/sys/arm64/arm64/vm_machdep.c
--- a/sys/arm64/arm64/vm_machdep.c
+++ b/sys/arm64/arm64/vm_machdep.c
@@ -102,7 +102,7 @@
 	/* Set the return value registers for fork() */
 	td2->td_pcb->pcb_x[8] = (uintptr_t)fork_return;
 	td2->td_pcb->pcb_x[9] = (uintptr_t)td2;
-	td2->td_pcb->pcb_x[PCB_LR] = (uintptr_t)fork_trampoline;
+	td2->td_pcb->pcb_lr = (uintptr_t)fork_trampoline;
 	td2->td_pcb->pcb_sp = (uintptr_t)td2->td_frame;
 	td2->td_pcb->pcb_fpusaved = &td2->td_pcb->pcb_fpustate;
 	td2->td_pcb->pcb_vfpcpu = UINT_MAX;
@@ -173,7 +173,7 @@
 
 	td->td_pcb->pcb_x[8] = (uintptr_t)fork_return;
 	td->td_pcb->pcb_x[9] = (uintptr_t)td;
-	td->td_pcb->pcb_x[PCB_LR] = (uintptr_t)fork_trampoline;
+	td->td_pcb->pcb_lr = (uintptr_t)fork_trampoline;
 	td->td_pcb->pcb_sp = (uintptr_t)td->td_frame;
 	td->td_pcb->pcb_fpusaved = &td->td_pcb->pcb_fpustate;
 	td->td_pcb->pcb_vfpcpu = UINT_MAX;
@@ -265,7 +265,7 @@
 
 	td->td_pcb->pcb_x[8] = (uintptr_t)func;
 	td->td_pcb->pcb_x[9] = (uintptr_t)arg;
-	td->td_pcb->pcb_x[PCB_LR] = (uintptr_t)fork_trampoline;
+	td->td_pcb->pcb_lr = (uintptr_t)fork_trampoline;
 	td->td_pcb->pcb_sp = (uintptr_t)td->td_frame;
 	td->td_pcb->pcb_fpusaved = &td->td_pcb->pcb_fpustate;
 	td->td_pcb->pcb_vfpcpu = UINT_MAX;
diff --git a/sys/arm64/include/db_machdep.h b/sys/arm64/include/db_machdep.h
--- a/sys/arm64/include/db_machdep.h
+++ b/sys/arm64/include/db_machdep.h
@@ -43,7 +43,7 @@
 typedef vm_offset_t	db_addr_t;
 typedef long		db_expr_t;
 
-#define	PC_REGS()	((db_addr_t)kdb_thrctx->pcb_pc)
+#define	PC_REGS()	((db_addr_t)kdb_thrctx->pcb_lr)
 
 #define	BKPT_INST	(0xd4200000)
 #define	BKPT_SIZE	(4)
diff --git a/sys/arm64/include/pcb.h b/sys/arm64/include/pcb.h
--- a/sys/arm64/include/pcb.h
+++ b/sys/arm64/include/pcb.h
@@ -36,10 +36,10 @@
 
 struct trapframe;
 
-#define	PCB_LR		30
 struct pcb {
-	uint64_t	pcb_x[31];
-	uint64_t	pcb_pc;
+	uint64_t	pcb_x[30];
+	uint64_t	pcb_lr;
+	uint64_t	_reserved;	/* Was pcb_pc */
 	/* These two need to be in order as we access them together */
 	uint64_t	pcb_sp;
 	uint64_t	pcb_tpidr_el0;