diff --git a/~/C/libserialport/listen.c b/~/C/libserialport/listen.c
index ced4d2c..6ce3f3b 100644
--- a/~/C/libserialport/listen.c
+++ b/~/C/libserialport/listen.c
@@ -8,7 +8,7 @@ int check(enum sp_return result);
 
 int main(int argc, char **argv) {
   struct sp_port *serial_port;
-  char *port_name = "/dev/ttyACM0";
+  char *port_name;
 
   const int size = 256;
   char *buffer = malloc(size + 1);
@@ -16,8 +16,33 @@ int main(int argc, char **argv) {
   const unsigned int timeout = 1000;
   int result;
 
+  /* Get the port name from the command line. */
   if (argc != 2) {
-    printf("Usage: %s <port>\n", argv[0]);
+    printf("Usage: %s <port>\n\n", argv[0]);
+
+    struct sp_port **port_list;
+    enum sp_return result = sp_list_ports(&port_list);
+
+    /* Getting the available ports. */
+    if (result != SP_OK) {
+      puts("Getting available ports failed!");
+    } else {
+      puts("Available ports:");
+
+      int i;
+      for (i = 0; port_list[i] != NULL; i++) {
+        /* Get the name of the port. */
+        struct sp_port *port = port_list[i];
+        char *port_name = sp_get_port_name(port);
+
+        printf("  * %s\n", port_name);
+      }
+
+      printf("\nAvailable %d ports.\n", i);
+
+      sp_free_port_list(port_list);
+    }
+
     return -1;
   } else {
     port_name = argv[1];
@@ -34,18 +59,24 @@ int main(int argc, char **argv) {
   check(sp_set_flowcontrol(serial_port, SP_FLOWCONTROL_NONE));
   puts("Connected.");
 
-
-  while (true) {
+  /* Reading lines from serial port. */
+  bool reading = true;
+  while (reading) {
     int pos = 0;
 
+    /* Character-by-character reading. */
     while (pos < size) {
       result = check(sp_blocking_read(serial_port, buffer + pos, 1, timeout));
 
       if (result == -1) {
         puts("Error reading from serial port");
+
+        reading = false;
         break;
       } else if (result == 0) {
         puts("No more data");
+
+        reading = false;
         break;
       } else {
         if (buffer[pos] == '\n') {