diff --git a/drivers/modem/modem_cellular.c b/drivers/modem/modem_cellular.c
index 9ddd881b7a..7c9e672853 100644
--- a/drivers/modem/modem_cellular.c
+++ b/drivers/modem/modem_cellular.c
@@ -28,7 +28,7 @@ LOG_MODULE_REGISTER(modem_cellular, CONFIG_MODEM_LOG_LEVEL);
 
 #define MODEM_CELLULAR_DATA_IMEI_LEN         (16)
 #define MODEM_CELLULAR_DATA_MODEL_ID_LEN     (65)
-#define MODEM_CELLULAR_DATA_IMSI_LEN         (22)
+#define MODEM_CELLULAR_DATA_IMSI_LEN         (23)
 #define MODEM_CELLULAR_DATA_ICCID_LEN        (22)
 #define MODEM_CELLULAR_DATA_MANUFACTURER_LEN (65)
 #define MODEM_CELLULAR_DATA_FW_VERSION_LEN   (65)