diff --git a/man/tio.1.in b/man/tio.1.in
index c37f225..c3658a3 100644
--- a/man/tio.1.in
+++ b/man/tio.1.in
@@ -57,7 +57,7 @@ option is provided, tio will exit if the device is not present or an established
 Enable local echo.
 
 .TP
-.BR \-t ", " \-\-timestamp[=<format>]
+.BR \-t ", " \-\-timestamp[=\fI<format>\fR\fB]
 
 Enable timestamp. Optionally you can specify any of the following timestamp formats:
 .RS
@@ -79,9 +79,9 @@ Default format is
 List available serial devices.
 
 .TP
-.BR \-l ", " "\-\-log " \fI<filename>
+.BR \-l ", " \-\-log[=\fI<filename>\fR\fB]
 
-Log to file.
+Log to file. If no filename is provided the filename will be automatically generated.
 
 .TP
 .BR \-m ", " "\-\-map " \fI<flags>
diff --git a/src/log.c b/src/log.c
index 9b2c15e..4aa774f 100644
--- a/src/log.c
+++ b/src/log.c
@@ -24,6 +24,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
+#include <time.h>
+#include <sys/time.h>
+#include <libgen.h>
 #include "options.h"
 #include "print.h"
 #include "error.h"
@@ -31,8 +34,32 @@
 static FILE *fp;
 static bool log_error = false;
 
+static char *date_time(void)
+{
+    static char date_time_string[50];
+    struct tm *tm;
+    struct timeval tv;
+
+    gettimeofday(&tv, NULL);
+
+    tm = localtime(&tv.tv_sec);
+    strftime(date_time_string, sizeof(date_time_string), "%Y-%m-%dT%H:%M:%S", tm);
+
+    return date_time_string;
+}
+
 void log_open(const char *filename)
 {
+    static char automatic_filename[400];
+
+    if (filename == NULL)
+    {
+        // Generate filename if none provided ("tio_DEVICE_YYYY-MM-DDTHH:MM:SS.log")
+        sprintf(automatic_filename, "tio_%s_%s.log", basename((char *)option.tty_device), date_time());
+        filename = automatic_filename;
+        option.log_filename = automatic_filename;
+    }
+
     fp = fopen(filename, "w+");
 
     if (fp == NULL)
@@ -46,20 +73,32 @@ void log_open(const char *filename)
 void log_write(char c)
 {
     if (fp != NULL)
+    {
         fputc(c, fp);
+    }
 }
 
 void log_close(void)
 {
     if (fp != NULL)
+    {
         fclose(fp);
+    }
 }
 
 void log_exit(void)
 {
     if (option.log)
+    {
         log_close();
+    }
 
     if (log_error)
+    {
         error_printf("Could not open log file %s (%s)", option.log_filename, strerror(errno));
+    }
+    else
+    {
+        tio_printf("Saved log to file %s", option.log_filename);
+    }
 }
diff --git a/src/options.c b/src/options.c
index ed68437..09eab0a 100644
--- a/src/options.c
+++ b/src/options.c
@@ -68,7 +68,7 @@ void print_help(char *argv[])
     printf("  -e, --local-echo            Enable local echo\n");
     printf("  -t, --timestamp[=<format>]  Enable timestamp (default: 24hour)\n");
     printf("  -L, --list-devices          List available serial devices\n");
-    printf("  -l, --log <filename>        Log to file\n");
+    printf("  -l, --log[=<filename>]      Log to file\n");
     printf("  -m, --map <flags>           Map special characters\n");
     printf("  -c, --color <0..255>        Colorize tio text\n");
     printf("  -v, --version               Display version\n");
@@ -120,7 +120,7 @@ void parse_options(int argc, char *argv[])
             {"local-echo",     no_argument,       0, 'e'},
             {"timestamp",      optional_argument, 0, 't'},
             {"list-devices",   no_argument,       0, 'L'},
-            {"log",            required_argument, 0, 'l'},
+            {"log",            optional_argument, 0, 'l'},
             {"map",            required_argument, 0, 'm'},
             {"color",          required_argument, 0, 'c'},
             {"version",        no_argument,       0, 'v'},
@@ -132,7 +132,7 @@ void parse_options(int argc, char *argv[])
         int option_index = 0;
 
         /* Parse argument using getopt_long */
-        c = getopt_long(argc, argv, "b:d:f:s:p:o:net::Ll:m:c:vh", long_options, &option_index);
+        c = getopt_long(argc, argv, "b:d:f:s:p:o:net::Ll::m:c:vh", long_options, &option_index);
 
         /* Detect the end of the options */
         if (c == -1)