diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index 401808b47af3..f3ffd0a3a012 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -131,8 +131,8 @@ static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
 	cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
 
 	/* Check whether this particular cx_type (in CST) is supported or not */
-	cstate_type = ((cx->address >> MWAIT_SUBSTATE_SIZE) &
-			MWAIT_CSTATE_MASK) + 1;
+	cstate_type = (((cx->address >> MWAIT_SUBSTATE_SIZE) &
+			MWAIT_CSTATE_MASK) + 1) & MWAIT_CSTATE_MASK;
 	edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
 	num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;
 
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index bcf1198e8991..e486027f8b07 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -1934,7 +1934,8 @@ static void __init spr_idle_state_table_update(void)
 
 static bool __init intel_idle_verify_cstate(unsigned int mwait_hint)
 {
-	unsigned int mwait_cstate = MWAIT_HINT2CSTATE(mwait_hint) + 1;
+	unsigned int mwait_cstate = (MWAIT_HINT2CSTATE(mwait_hint) + 1) &
+					MWAIT_CSTATE_MASK;
 	unsigned int num_substates = (mwait_substates >> mwait_cstate * 4) &
 					MWAIT_SUBSTATE_MASK;