diff --git a/src/arch/fake/hypervisor/cpu.c b/src/arch/fake/hypervisor/cpu.c
index 8014b3f..3fc09f9 100644
--- a/src/arch/fake/hypervisor/cpu.c
+++ b/src/arch/fake/hypervisor/cpu.c
@@ -38,17 +38,17 @@
 void arch_regs_set_pc_arg(struct arch_regs *r, ipaddr_t pc, uintreg_t arg)
 {
 	(void)pc;
-	r->r[0] = arg;
+	r->arg[0] = arg;
 }
 
 void arch_regs_set_retval(struct arch_regs *r, struct spci_value v)
 {
-	r->r[0] = v.func;
-	r->r[1] = v.arg1;
-	r->r[2] = v.arg2;
-	r->r[3] = v.arg3;
-	r->r[4] = v.arg4;
-	r->r[5] = v.arg5;
-	r->r[6] = v.arg6;
-	r->r[7] = v.arg7;
+	r->arg[0] = v.func;
+	r->arg[1] = v.arg1;
+	r->arg[2] = v.arg2;
+	r->arg[3] = v.arg3;
+	r->arg[4] = v.arg4;
+	r->arg[5] = v.arg5;
+	r->arg[6] = v.arg6;
+	r->arg[7] = v.arg7;
 }
diff --git a/src/arch/fake/inc/hf/arch/types.h b/src/arch/fake/inc/hf/arch/types.h
index 24e16ae..4cb5be4 100644
--- a/src/arch/fake/inc/hf/arch/types.h
+++ b/src/arch/fake/inc/hf/arch/types.h
@@ -46,7 +46,7 @@
 
 /** Type to represent the register state of a VM.  */
 struct arch_regs {
-	uintreg_t r[8];
+	uintreg_t arg[8];
 	cpu_id_t vcpu_id;
 	bool virtual_interrupt;
 };