diff --git a/hw/gpio/aspeed_gpio.c b/hw/gpio/aspeed_gpio.c
index 3e7b35c..7175666 100644
--- a/hw/gpio/aspeed_gpio.c
+++ b/hw/gpio/aspeed_gpio.c
@@ -281,7 +281,7 @@
     diff &= mode_mask;
     if (diff) {
         for (gpio = 0; gpio < ASPEED_GPIOS_PER_SET; gpio++) {
-            uint32_t mask = 1 << gpio;
+            uint32_t mask = 1U << gpio;
 
             /* If the gpio needs to be updated... */
             if (!(diff & mask)) {