diff --git a/chip/npcx/shi.c b/chip/npcx/shi.c
index 6cf030cf7c..154bc3a5d7 100644
--- a/chip/npcx/shi.c
+++ b/chip/npcx/shi.c
@@ -195,13 +195,15 @@ static uint8_t shi_read_buf_pointer(void);
  */
 static void shi_send_response_packet(struct host_packet *pkt)
 {
+	/*
+	 * Disable interrupts. This routine is not called from interrupt
+	 * context and buffer underrun will likely occur if it is
+	 * preempted after writing its initial reply byte. Also, we must be
+	 * sure our state doesn't unexpectedly change, in case we're expected
+	 * to take RESP_NOT_RDY actions.
+	 */
+	interrupt_disable();
 	if (state == SHI_STATE_PROCESSING) {
-		/*
-		* Disable interrupts. This routine is not called from interrupt
-		* context and buffer underrun will likely occur if it is
-		* preempted after writing its initial reply byte.
-		*/
-		interrupt_disable();
 
 		/* Append our past-end byte, which we reserved space for. */
 		((uint8_t *) pkt->response)[pkt->response_size + 0] =
@@ -226,8 +228,6 @@ static void shi_send_response_packet(struct host_packet *pkt)
 #ifdef NPCX_SHI_BYPASS_OVER_256B
 		}
 #endif
-
-		interrupt_enable();
 	}
 	/*
 	 * If we're not processing, then the AP has already terminated the
@@ -239,6 +239,8 @@ static void shi_send_response_packet(struct host_packet *pkt)
 		DEBUG_CPRINTF("END\n");
 	} else
 		DEBUG_CPRINTS("Unexpected state %d in response handler", state);
+
+	interrupt_enable();
 }
 
 void shi_handle_host_package(void)
@@ -293,9 +295,6 @@ void shi_handle_host_package(void)
 /* Parse header for version of spi-protocol */
 static void shi_parse_header(void)
 {
-	/* Disable SHI interrupt until we're sure the size of request package.*/
-	task_disable_irq(NPCX_IRQ_SHI);
-
 	/* We're now inside a transaction */
 	state = SHI_STATE_RECEIVING;
 	DEBUG_CPRINTF("RV-");
@@ -330,9 +329,6 @@ static void shi_parse_header(void)
 		/* Computing total bytes need to receive */
 		shi_params.sz_request = pkt_size;
 
-		/* Enable SHI interrupt & handle request package */
-		task_enable_irq(NPCX_IRQ_SHI);
-
 		shi_handle_host_package();
 	} else {
 		/* Invalid version number */
@@ -501,12 +497,6 @@ static void shi_bad_received_data(void)
 		CPRINTF("%02x ", in_msg[i]);
 	CPRINTF("]\n");
 
-	/*
-	 * Enable SHI interrupt again since we disable it
-	 * at the begin of SHI_STATE_RECEIVING state
-	 */
-	task_enable_irq(NPCX_IRQ_SHI);
-
 	/* Reset shi's state machine for error recovery */
 	shi_reset_prepare();
 
@@ -559,6 +549,14 @@ void shi_int_handler(void)
 			shi_fill_out_status(EC_SPI_NOT_READY);
 
 			state = SHI_STATE_CNL_RESP_NOT_RDY;
+
+			/*
+			 * Disable SHI interrupt, it will remain disabled
+			 * until shi_send_response_packet() is called and
+			 * CS is asserted for a new transaction.
+			 */
+			task_disable_irq(NPCX_IRQ_SHI);
+
 			DEBUG_CPRINTF("CNL-");
 			return;
 		/* Next transaction but we're not ready */
@@ -684,6 +682,12 @@ void shi_cs_event(enum gpio_signal signal)
 
 	DEBUG_CPRINTF("CSL-");
 
+	/*
+	 * Enable SHI interrupt - we will either succeed to parse our host
+	 * command or reset on failure from here.
+	 */
+	task_enable_irq(NPCX_IRQ_SHI);
+
 	/* Read first three bytes to parse which protocol is receiving */
 	shi_parse_header();
 }
@@ -699,6 +703,9 @@ static void shi_reset_prepare(void)
 {
 	uint16_t i;
 
+	/* We no longer care about SHI interrupts, so disable them. */
+	task_disable_irq(NPCX_IRQ_SHI);
+
 	/* Initialize parameters of next transaction */
 	shi_params.rx_msg = in_msg;
 	shi_params.tx_msg = out_msg;
@@ -735,6 +742,7 @@ static void shi_reset_prepare(void)
 static void shi_enable(void)
 {
 	int gpio_flags;
+	int shi_cs_level;
 
 	shi_reset_prepare();
 
@@ -754,8 +762,23 @@ static void shi_enable(void)
 	 */
 	SET_BIT(NPCX_DEVALT(ALT_GROUP_C), NPCX_DEVALTC_SHI_SL);
 
+	/*
+	 * If CS is already asserted prior to enabling our GPIO interrupt then
+	 * we have missed the falling edge and we need to handle the
+	 * deassertion interrupt - to do so, we'll enable the SHI interrupt
+	 * later.
+	 */
+	shi_cs_level = gpio_get_level(GPIO_SHI_CS_L);
+
 	/* Enable SHI_CS_L interrupt */
 	gpio_enable_interrupt(GPIO_SHI_CS_L);
+
+	/*
+	 * Check the CS level again, in case it was asserted after our previous
+	 * check.
+	 */
+	if (!shi_cs_level || !gpio_get_level(GPIO_SHI_CS_L))
+		task_enable_irq(NPCX_IRQ_SHI);
 }
 DECLARE_HOOK(HOOK_CHIPSET_RESUME, shi_enable, HOOK_PRIO_DEFAULT);