diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9f09a41..5cef06f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,10 @@
 # Changelog
 Date format : day/month/year
 
+## 1.9.0 - ??/??/2022 - Foundry v10 Compatibility
+- Updated the System to FoundryVTT v10.
+- Added a `game.user.isFirstGM` property for some traitements (socket and migration) to prevent multiple executions with multiple GM connected.
+
 ## 1.8.2 - 24/06/2022 - Unofficial Italian translation
 - Added Unofficial Italian translation (Corebook only for compendiums), all thanks to EldritchTranslator.
 - Added French translation for Tables.
diff --git a/system/scripts/dice/roll-n-keep-dialog.js b/system/scripts/dice/roll-n-keep-dialog.js
index 907666f..dcce4a3 100644
--- a/system/scripts/dice/roll-n-keep-dialog.js
+++ b/system/scripts/dice/roll-n-keep-dialog.js
@@ -676,7 +676,7 @@ export class RollnKeepDialog extends FormApplication {
 
         // Delete old chat message related to this series
         if (game.settings.get("l5r5e", "rnk-deleteOldMessage")) {
-            if (game.user.isGM) {
+            if (game.user.isFirstGM) {
                 const message = game.messages.get(msgOldId);
                 if (message) {
                     message.delete();
diff --git a/system/scripts/hooks.js b/system/scripts/hooks.js
index 75bd5cc..970ef92 100644
--- a/system/scripts/hooks.js
+++ b/system/scripts/hooks.js
@@ -16,6 +16,13 @@ export default class HooksL5r5e {
      * Do anything once the system is ready
      */
     static async ready() {
+        // If multiple GM connected, tag the 1st alive, useful for some traitements
+        Object.defineProperty(game.user, "isFirstGM", {
+            get: function () {
+                return game.user.isGM && game.user.id === game.users.find((u) => u.active && u.isGM)?.id;
+            },
+        });
+
         // Migration stuff
         if (game.l5r5e.migrations.needUpdate(game.l5r5e.migrations.NEEDED_VERSION)) {
             game.l5r5e.migrations.migrateWorld({ force: false });
diff --git a/system/scripts/migration.js b/system/scripts/migration.js
index 8c70890..bcb6ef1 100644
--- a/system/scripts/migration.js
+++ b/system/scripts/migration.js
@@ -24,7 +24,7 @@ export class MigrationL5r5e {
      * @return {Promise<void>} A Promise which resolves once the migration is completed
      */
     static async migrateWorld(options = { force: false }) {
-        if (!game.user.isGM) {
+        if (!game.user.isFirstGM) {
             return;
         }
 
diff --git a/system/scripts/socket-handler.js b/system/scripts/socket-handler.js
index e5512ea..e063d44 100644
--- a/system/scripts/socket-handler.js
+++ b/system/scripts/socket-handler.js
@@ -44,9 +44,9 @@ export class SocketHandlerL5r5e {
         });
     }
     _onDeleteChatMessage(data) {
-        // Only delete the message if the user is a GM (otherwise it have no real effect)
+        // Only delete the message if the user is a GM (otherwise it has no real effect)
         // Currently only used in RnK
-        if (!game.user.isGM || !game.settings.get("l5r5e", "rnk-deleteOldMessage")) {
+        if (!game.user.isFirstGM || !game.settings.get("l5r5e", "rnk-deleteOldMessage")) {
             return;
         }
         const message = game.messages.get(data.messageId);
diff --git a/system/system.json b/system/system.json
index 3a17190..e54c09c 100644
--- a/system/system.json
+++ b/system/system.json
@@ -6,8 +6,8 @@
     "readme": "https://gitlab.com/teaml5r/l5r5e/-/blob/master/README.md",
     "changelog": "https://gitlab.com/teaml5r/l5r5e/-/blob/master/CHANGELOG.md",
     "manifest": "https://gitlab.com/teaml5r/l5r5e/-/raw/master/system/system.json",
-    "download": "https://gitlab.com/teaml5r/l5r5e/-/jobs/artifacts/v1.8.2/raw/l5r5e.zip?job=build",
-    "version": "1.8.2",
+    "download": "https://gitlab.com/teaml5r/l5r5e/-/jobs/artifacts/v1.9.0/raw/l5r5e.zip?job=build",
+    "version": "1.9.0",
     "minimumCoreVersion": "9",
     "compatibleCoreVersion": "9",
     "manifestPlusVersion": "1.2.0",