diff --git a/src/soc/intel/broadwell/pch/power_state.c b/src/soc/intel/broadwell/pch/power_state.c
index cb1d3e5..12bee7d 100644
--- a/src/soc/intel/broadwell/pch/power_state.c
+++ b/src/soc/intel/broadwell/pch/power_state.c
@@ -33,7 +33,7 @@
 ROMSTAGE_CBMEM_INIT_HOOK(migrate_power_state)
 
 /* Return 0, 3, or 5 to indicate the previous sleep state. */
-static int prev_sleep_state(struct chipset_power_state *ps)
+static int prev_sleep_state(const struct chipset_power_state *ps)
 {
 	/* Default to S0. */
 	int prev_sleep_state = ACPI_S0;