diff --git a/Base/usr/share/man/man1/mkdir.md b/Base/usr/share/man/man1/mkdir.md
index 02cf81fa4b..7f89f074b8 100644
--- a/Base/usr/share/man/man1/mkdir.md
+++ b/Base/usr/share/man/man1/mkdir.md
@@ -15,13 +15,15 @@ Create a new empty directory for each of the given *directories*.
 ## Options
 
 * `-p`, `--parents`: Create parent directories if they don't exist
-* `-m`, `--mode`: Sets the permissions for the final directory (possibly altered by the process umask). The mode argument must be given in octal format.
+* `-m`, `--mode`: Sets the permissions for the final directory (possibly altered by the process umask). The mode argument can be given in any of the formats
+accepted by the chmod(1) command. Addition and removal of permissions is relative to a default permission of 0777.
 
 ## Examples
 
 ```sh
 $ mkdir -p /tmp/foo/bar
 $ mkdir -m 0700 /tmp/owner-only
+$ mkdir -m a=rx /tmp/foo/bar
 ```
 
 ## See also
diff --git a/Userland/Utilities/mkdir.cpp b/Userland/Utilities/mkdir.cpp
index 72d24b499a..156fd1b2ca 100644
--- a/Userland/Utilities/mkdir.cpp
+++ b/Userland/Utilities/mkdir.cpp
@@ -1,14 +1,15 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
  * Copyright (c) 2020-2021, Linus Groh <linusg@serenityos.org>
+ * Copyright (c) 2021, Xavier Defrang <xavier.defrang@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include <AK/LexicalPath.h>
 #include <AK/StringBuilder.h>
-#include <AK/StringUtils.h>
 #include <LibCore/ArgsParser.h>
+#include <LibCore/FilePermissionsMask.h>
 #include <LibCore/System.h>
 #include <LibMain/Main.h>
 #include <errno.h>
@@ -25,19 +26,19 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     Core::ArgsParser args_parser;
     args_parser.add_option(create_parents, "Create parent directories if they don't exist", "parents", 'p');
-    args_parser.add_option(mode_string, "Set new directory permissions", "mode", 'm', "octal-mode");
+    args_parser.add_option(mode_string, "Set new directory permissions", "mode", 'm', "mode");
     args_parser.add_positional_argument(directories, "Directories to create", "directories");
     args_parser.parse(arguments);
 
-    mode_t default_mode = 0755;
-    mode_t mode = default_mode;
+    mode_t const default_mode = 0755;
+    mode_t const mask_reference_mode = 0777;
 
-    if (!mode_string.is_empty()) {
-        mode = AK::StringUtils::convert_to_uint_from_octal<u16>(mode_string).value_or(01000);
-        if (mode > 0777) {
-            warnln("mkdir: invalid mode: {}", mode_string);
-            return 1;
-        }
+    Core::FilePermissionsMask mask;
+
+    if (mode_string.is_empty()) {
+        mask.assign_permissions(default_mode);
+    } else {
+        mask = TRY(Core::FilePermissionsMask::parse(mode_string));
     }
 
     bool has_errors = false;
@@ -45,7 +46,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     for (auto& directory : directories) {
         LexicalPath lexical_path(directory);
         if (!create_parents) {
-            if (mkdir(lexical_path.string().characters(), mode) < 0) {
+            if (mkdir(lexical_path.string().characters(), mask.apply(mask_reference_mode)) < 0) {
                 perror("mkdir");
                 has_errors = true;
             }
@@ -73,8 +74,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 }
 
                 bool is_final = (idx == (num_parts - 1));
+                mode_t mode = is_final ? mask.apply(mask_reference_mode) : default_mode;
 
-                if (mkdir(path.characters(), is_final ? mode : default_mode) < 0) {
+                if (mkdir(path.characters(), mode) < 0) {
                     perror("mkdir");
                     has_errors = true;
                     break;