diff --git a/src/pickit5.c b/src/pickit5.c
index 8cb6e357..d0cbb9c3 100644
--- a/src/pickit5.c
+++ b/src/pickit5.c
@@ -573,6 +573,7 @@ static int pickit5_open(PROGRAMMER *pgm, const char *port) {
   union pinfo pinfo;
   LNODEID usbpid;
   int rv = LIBAVRDUDE_GENERAL_FAILURE;
+  size_t serial_num_len = 0;
 
 #if !defined(HAVE_LIBUSB)
   pmsg_error("need to be compiled with USB or HIDAPI support\n");
@@ -580,7 +581,7 @@ static int pickit5_open(PROGRAMMER *pgm, const char *port) {
 #endif
 
   if(!str_starts(port, "usb:") && !str_eq(port, "usb")) {
-    pmsg_error("invalid -P %s; use -P usb:<vid>:<pid>, -P usb:<serialno> or -P usb\n", port);
+    pmsg_error("invalid -P %s; drop -P option or else use -P usb:<vid>:<pid> or -P usb:<serialno>\n", port);
     return LIBAVRDUDE_GENERAL_FAILURE;
   }
   unsigned int new_vid = 0, new_pid = 0, setids = 0;
@@ -627,8 +628,10 @@ static int pickit5_open(PROGRAMMER *pgm, const char *port) {
 
       pmsg_notice("overwriting VID:PID to %04x:%04x\n", new_vid, new_pid);
       port = "usb";             // Overwrite the string to avoid confusing the libusb
-    }                           // pidp == NULL means vidp could point to serial number
-  }                             // vidp == NULL means just 'usb'
+    } else {                    // pidp == NULL means vidp points to serial number
+      serial_num_len = strlen(vidp);
+    }
+  }                             // vidp == NULL means dropped -P option or -P usb
 
   // If the config entry did not specify a USB PID, insert the default one
   if(lfirst(pgm->usbpid) == NULL)
@@ -728,6 +731,11 @@ static int pickit5_open(PROGRAMMER *pgm, const char *port) {
       serial_close(&pgm->fd);
       return LIBAVRDUDE_EXIT;
     }
+    if(serial_num_len) {
+      pmsg_error("no device found matching the specified serial number %s", vidp);
+      return LIBAVRDUDE_GENERAL_FAILURE;
+    }
+
     pmsg_error("no device found matching VID 0x%04x and PID list: 0x%04x, 0x%04x, 0x%04x\n", USB_VENDOR_MICROCHIP,
       USB_DEVICE_PICKIT5, USB_DEVICE_PICKIT4_PIC_MODE, USB_DEVICE_SNAP_PIC_MODE);
     imsg_error("nor VID 0x%04x with PID list: 0x%04x, 0x%04x\n", USB_VENDOR_ATMEL, USB_DEVICE_PICKIT4_AVR_MODE, USB_DEVICE_SNAP_AVR_MODE);