diff --git a/src/machine/machine_rp2_gpio.go b/src/machine/machine_rp2_gpio.go
index 6854f8aad..25d76261f 100644
--- a/src/machine/machine_rp2_gpio.go
+++ b/src/machine/machine_rp2_gpio.go
@@ -33,6 +33,7 @@ type irqSummary struct {
 
 type ioBank0Type struct {
 	io                 [_NUMBANK0_GPIOS]ioType
+	_                  [rp2350ExtraReg][128]byte
 	irqsum             [rp2350ExtraReg]irqSummary
 	intR               [_NUMBANK0_IRQS]volatile.Register32
 	proc0IRQctrl       irqCtrl