diff --git a/lib/lists/custom_emojies_list.dart b/lib/lists/custom_emojies_list.dart
index d967008..043ec56 100644
--- a/lib/lists/custom_emojies_list.dart
+++ b/lib/lists/custom_emojies_list.dart
@@ -6,6 +6,10 @@ import 'package:comunic/models/custom_emoji.dart';
 /// @author Pierre HUBERT
 
 class CustomEmojiesList extends AbstractList<CustomEmoji> {
+  /// Check if an emoji, identified by its shortcut, is present in this list
+  bool hasShortcut(String shortcut) =>
+      firstWhere((f) => f.shortcut == shortcut, orElse: () => null) != null;
+
   /// Serialize this list
   List<Map<String, dynamic>> toSerializableList() =>
       map((f) => f.toMap()).toList();
diff --git a/lib/ui/routes/account_settings/custom_emojies_account_settings.dart b/lib/ui/routes/account_settings/custom_emojies_account_settings.dart
index b34985c..953a67f 100644
--- a/lib/ui/routes/account_settings/custom_emojies_account_settings.dart
+++ b/lib/ui/routes/account_settings/custom_emojies_account_settings.dart
@@ -2,6 +2,7 @@ import 'dart:io';
 
 import 'package:comunic/helpers/settings_helper.dart';
 import 'package:comunic/helpers/users_helper.dart';
+import 'package:comunic/lists/custom_emojies_list.dart';
 import 'package:comunic/models/new_emoji.dart';
 import 'package:comunic/models/user.dart';
 import 'package:comunic/ui/widgets/async_screen_widget.dart';
@@ -90,7 +91,9 @@ class _CustomEmojiesAccountBodyState extends State<_CustomEmojiesAccountBody> {
     try {
       final newEmoji = await showDialog<NewEmoji>(
         context: context,
-        builder: (c) => _NewCustomEmojiDialog(),
+        builder: (c) => _NewCustomEmojiDialog(
+          currentList: _user.customEmojies,
+        ),
       );
 
       if (newEmoji == null) return;
@@ -107,6 +110,14 @@ class _CustomEmojiesAccountBodyState extends State<_CustomEmojiesAccountBody> {
 
 /// Dialog used to upload new custom emojies
 class _NewCustomEmojiDialog extends StatefulWidget {
+  final CustomEmojiesList currentList;
+
+  const _NewCustomEmojiDialog({
+    Key key,
+    @required this.currentList,
+  })  : assert(currentList != null),
+        super(key: key);
+
   @override
   _NewCustomEmojiDialogState createState() => _NewCustomEmojiDialogState();
 }
@@ -120,7 +131,9 @@ class _NewCustomEmojiDialogState extends State<_NewCustomEmojiDialog> {
   String get _shortcut => _controller.text;
 
   bool get _shortcutValid =>
-      _shortcut.isNotEmpty && validateShortcut(_shortcut);
+      _shortcut.isNotEmpty &&
+      validateShortcut(_shortcut) &&
+      !widget.currentList.hasShortcut(_shortcut);
 
   bool get _valid => _hasImage && _shortcutValid;