diff --git a/src/ls.c b/src/ls.c
index 9549130..e5b772f 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -836,6 +836,7 @@ static struct option const long_options[] =
   {"block-size", required_argument, NULL, BLOCK_SIZE_OPTION},
   {"context", no_argument, 0, 'Z'},
   {"author", no_argument, NULL, AUTHOR_OPTION},
+  {"digit-group", no_argument, NULL, 'y'},
   {GETOPT_HELP_OPTION_DECL},
   {GETOPT_VERSION_OPTION_DECL},
   {NULL, 0, NULL, 0}
@@ -1639,7 +1640,7 @@ decode_switches (int argc, char **argv)
     {
       int oi = -1;
       int c = getopt_long (argc, argv,
-                           "abcdfghiklmnopqrstuvw:xABCDFGHI:LNQRST:UXZ1",
+                           "abcdfghiklmnopqrstuvw:xyABCDFGHI:LNQRST:UXZ1",
                            long_options, &oi);
       if (c == -1)
         break;
@@ -1760,6 +1761,10 @@ decode_switches (int argc, char **argv)
           format = horizontal;
           break;
 
+        case 'y':
+          human_output_opts = human_group_digits;
+          break;
+
         case 'A':
           if (ignore_mode == IGNORE_DEFAULT)
             ignore_mode = IGNORE_DOT_AND_DOTDOT;
@@ -4708,6 +4713,8 @@ Mandatory arguments to long options are mandatory for short options too.\n\
   -w, --width=COLS           assume screen width instead of current value\n\
   -x                         list entries by lines instead of by columns\n\
   -X                         sort alphabetically by entry extension\n\
+  -y, --digit-group          with -l, group digits of file size\n\
+
   -Z, --context              print any SELinux security context of each file\n\
   -1                         list one file per line\n\
 "), stdout);