diff --git a/subsys/usb/usb_c/usbc_pe_common.c b/subsys/usb/usb_c/usbc_pe_common.c
index bda497f7c10..23499072c97 100644
--- a/subsys/usb/usb_c/usbc_pe_common.c
+++ b/subsys/usb/usb_c/usbc_pe_common.c
@@ -343,6 +343,7 @@ void pe_set_state(const struct device *dev, const enum usbc_pe_state state)
 {
 	struct usbc_port_data *data = dev->data;
 
+	__ASSERT(state < ARRAY_SIZE(pe_states), "invalid pe_state %d", state);
 	smf_set_state(SMF_CTX(data->pe), &pe_states[state]);
 }
 
@@ -823,3 +824,4 @@ static const struct smf_state pe_states[] = {
 		NULL,
 		NULL),
 };
+BUILD_ASSERT(ARRAY_SIZE(pe_states) == PE_STATE_COUNT);
diff --git a/subsys/usb/usb_c/usbc_pe_common_internal.h b/subsys/usb/usb_c/usbc_pe_common_internal.h
index fc441600d9f..62bf93fb1f0 100644
--- a/subsys/usb/usb_c/usbc_pe_common_internal.h
+++ b/subsys/usb/usb_c/usbc_pe_common_internal.h
@@ -55,6 +55,9 @@ enum usbc_pe_state {
 
 	/** PE_Suspend. Not part of the PD specification. */
 	PE_SUSPEND,
+
+	/** Number of PE States */
+	PE_STATE_COUNT
 };
 
 /**
diff --git a/subsys/usb/usb_c/usbc_prl.c b/subsys/usb/usb_c/usbc_prl.c
index 8aee0452edb..5984b9d04b6 100644
--- a/subsys/usb/usb_c/usbc_prl.c
+++ b/subsys/usb/usb_c/usbc_prl.c
@@ -70,6 +70,9 @@ enum usbc_prl_tx_state_t {
 
 	/** PRL_Tx_Suspend. Not part of the PD specification. */
 	PRL_TX_SUSPEND,
+
+	/** Number of PRL_TX States */
+	PRL_TX_STATE_COUNT
 };
 
 /**
@@ -87,6 +90,9 @@ enum usbc_prl_hr_state_t {
 
 	/** PRL_Hr_Suspend. Not part of the PD specification. */
 	PRL_HR_SUSPEND,
+
+	/** Number of PRL_HR States */
+	PRL_HR_STATE_COUNT
 };
 
 static const struct smf_state prl_tx_states[];
@@ -374,6 +380,7 @@ static void prl_tx_set_state(const struct device *dev, const enum usbc_prl_tx_st
 	struct usbc_port_data *data = dev->data;
 	struct protocol_layer_tx_t *prl_tx = data->prl_tx;
 
+	__ASSERT(state < ARRAY_SIZE(prl_tx_states), "invalid prl_tx_state %d", state);
 	smf_set_state(SMF_CTX(prl_tx), &prl_tx_states[state]);
 }
 
@@ -385,6 +392,7 @@ static void prl_hr_set_state(const struct device *dev, const enum usbc_prl_hr_st
 	struct usbc_port_data *data = dev->data;
 	struct protocol_hard_reset_t *prl_hr = data->prl_hr;
 
+	__ASSERT(state < ARRAY_SIZE(prl_hr_states), "invalid prl_hr_state %d", state);
 	smf_set_state(SMF_CTX(prl_hr), &prl_hr_states[state]);
 }
 
@@ -1159,6 +1167,7 @@ static const struct smf_state prl_tx_states[] = {
 		NULL,
 		NULL),
 };
+BUILD_ASSERT(ARRAY_SIZE(prl_tx_states) == PRL_TX_STATE_COUNT);
 
 /**
  * @brief Protocol Layer Hard Reset State table
@@ -1190,3 +1199,4 @@ static const struct smf_state prl_hr_states[] = {
 		NULL,
 		NULL),
 };
+BUILD_ASSERT(ARRAY_SIZE(prl_hr_states) == PRL_HR_STATE_COUNT);
diff --git a/subsys/usb/usb_c/usbc_tc_common.c b/subsys/usb/usb_c/usbc_tc_common.c
index 1cb5960226b..edc857e0e1f 100644
--- a/subsys/usb/usb_c/usbc_tc_common.c
+++ b/subsys/usb/usb_c/usbc_tc_common.c
@@ -127,6 +127,7 @@ void tc_set_state(const struct device *dev, const enum tc_state_t state)
 	struct usbc_port_data *data = dev->data;
 	struct tc_sm_t *tc = data->tc;
 
+	__ASSERT(state < ARRAY_SIZE(tc_states), "invalid tc_state %d", state);
 	smf_set_state(SMF_CTX(tc), &tc_states[state]);
 }
 
@@ -261,3 +262,4 @@ static const struct smf_state tc_states[] = {
 		NULL,
 		&tc_states[TC_CC_OPEN_SUPER_STATE]),
 };
+BUILD_ASSERT(ARRAY_SIZE(tc_states) == TC_STATE_COUNT);
diff --git a/subsys/usb/usb_c/usbc_tc_common_internal.h b/subsys/usb/usb_c/usbc_tc_common_internal.h
index da96ad118b3..94613a8db3f 100644
--- a/subsys/usb/usb_c/usbc_tc_common_internal.h
+++ b/subsys/usb/usb_c/usbc_tc_common_internal.h
@@ -33,6 +33,9 @@ enum tc_state_t {
 	TC_ATTACH_WAIT_SNK_STATE,
 	/** Attached Sink State */
 	TC_ATTACHED_SNK_STATE,
+
+	/** Number of TC States */
+	TC_STATE_COUNT
 };
 
 /**