diff --git a/drivers/tty/serial/jsm/jsm_cls.c b/drivers/tty/serial/jsm/jsm_cls.c
index bfb0681195b6..4eb12a9cae76 100644
--- a/drivers/tty/serial/jsm/jsm_cls.c
+++ b/drivers/tty/serial/jsm/jsm_cls.c
@@ -570,7 +570,7 @@ static inline void cls_parse_isr(struct jsm_board *brd, uint port)
 	 * verified in the interrupt routine.
 	 */
 
-	if (port > brd->nasync)
+	if (port >= brd->nasync)
 		return;
 
 	ch = brd->channels[port];
diff --git a/drivers/tty/serial/jsm/jsm_neo.c b/drivers/tty/serial/jsm/jsm_neo.c
index 7291c2117daa..932b2accd06f 100644
--- a/drivers/tty/serial/jsm/jsm_neo.c
+++ b/drivers/tty/serial/jsm/jsm_neo.c
@@ -724,7 +724,7 @@ static inline void neo_parse_isr(struct jsm_board *brd, u32 port)
 	if (!brd)
 		return;
 
-	if (port > brd->maxports)
+	if (port >= brd->maxports)
 		return;
 
 	ch = brd->channels[port];
@@ -840,7 +840,7 @@ static inline void neo_parse_lsr(struct jsm_board *brd, u32 port)
 	if (!brd)
 		return;
 
-	if (port > brd->maxports)
+	if (port >= brd->maxports)
 		return;
 
 	ch = brd->channels[port];
@@ -1180,7 +1180,7 @@ static irqreturn_t neo_intr(int irq, void *voidbrd)
 			 */
 
 			/* Verify the port is in range. */
-			if (port > brd->nasync)
+			if (port >= brd->nasync)
 				continue;
 
 			ch = brd->channels[port];