diff --git a/src/context.h b/src/context.h
index 346fd5d..22129a9 100644
--- a/src/context.h
+++ b/src/context.h
@@ -79,6 +79,9 @@ typedef struct nwipe_speedring_t_
 // Arbitrary length, so far most paths don't exceed about 25 characters
 #define MAX_HWMON_PATH_LENGTH 100
 
+// 20 chracters for serial number plus null Byte
+#define NWIPE_SERIALNUMBER_LENGTH 20
+
 typedef struct nwipe_context_t_
 {
     /*
@@ -109,7 +112,8 @@ typedef struct nwipe_context_t_
     nwipe_device_t device_type;  // Indicates an IDE, SCSI, or Compaq SMART device in enumerated form (int)
     char device_type_str[14];  // Indicates an IDE, SCSI, USB etc as per nwipe_device_t but in ascii
     int device_is_ssd;  // 0 = no SSD, 1 = is a SSD
-    char device_serial_no[21];  // Serial number(processed, 20 characters plus null termination) of the device.
+    char device_serial_no[NWIPE_SERIALNUMBER_LENGTH
+                          + 1];  // Serial number(processed, 20 characters plus null termination) of the device.
     int device_target;  // The device target.
 
     u64 eta;  // The estimated number of seconds until method completion.
diff --git a/src/device.c b/src/device.c
index 0678654..904492a 100644
--- a/src/device.c
+++ b/src/device.c
@@ -131,7 +131,7 @@ int check_device( nwipe_context_t*** c, PedDevice* dev, int dcount )
     int fd;
     int idx;
     int r;
-    char tmp_serial[21];
+    char tmp_serial[NWIPE_SERIALNUMBER_LENGTH + 1];
     nwipe_device_t bus;
     int is_ssd;
     int check_HPA;  // a flag that indicates whether we check for a HPA on this device
@@ -252,7 +252,7 @@ int check_device( nwipe_context_t*** c, PedDevice* dev, int dcount )
     ioctl( fd, HDIO_GET_IDENTITY, &next_device->identity );
     close( fd );
 
-    for( idx = 0; idx < 20; idx++ )
+    for( idx = 0; idx < NWIPE_SERIALNUMBER_LENGTH; idx++ )
     {
         if( isascii( next_device->identity.serial_no[idx] ) && !iscntrl( next_device->identity.serial_no[idx] ) )
         {
@@ -794,7 +794,8 @@ int nwipe_get_device_bus_type_and_serialno( char* device, nwipe_device_t* bus, i
                     /* strip any leading or trailing spaces and left justify, +15 is the length of "Serial Number:" */
                     trim( &result[15] );
 
-                    strncpy( serialnumber, &result[15], 20 );
+                    strncpy( serialnumber, &result[15], NWIPE_SERIALNUMBER_LENGTH );
+                    serialnumber[NWIPE_SERIALNUMBER_LENGTH] = 0;
                 }
 
                 if( *bus == 0 )
diff --git a/src/logging.c b/src/logging.c
index c288624..cb01e98 100644
--- a/src/logging.c
+++ b/src/logging.c
@@ -666,7 +666,7 @@ void nwipe_log_summary( nwipe_context_t** ptr, int nwipe_selected )
     // char duration[5];
     char duration[314];
     char model[18];
-    char serial_no[20];
+    char serial_no[NWIPE_SERIALNUMBER_LENGTH + 1];
     char exclamation_flag[2];
     int hours;
     int minutes;
@@ -875,7 +875,8 @@ void nwipe_log_summary( nwipe_context_t** ptr, int nwipe_selected )
         model[17] = 0;
 
         /* Serial No. */
-        strncpy( serial_no, c[i]->device_serial_no, 20 );
+        strncpy( serial_no, c[i]->device_serial_no, NWIPE_SERIALNUMBER_LENGTH );
+        serial_no[NWIPE_SERIALNUMBER_LENGTH] = 0;
         model[17] = 0;
 
         nwipe_log( NWIPE_LOG_NOTIMESTAMP,