diff --git a/src/css/options.css b/src/css/options.css
index 5a6baf0..99036f6 100644
--- a/src/css/options.css
+++ b/src/css/options.css
@@ -37,6 +37,16 @@ form {
   margin-block: 4px 8px;
 }
 
+.settings-group-column {
+  display: flex;
+  flex-direction: column;
+}
+
+.settings-group-column label,
+.settings-group-column p {
+  margin-block: 4px 8px;
+}
+
 input[type="checkbox"] {
   margin-inline: 0 8px;
   margin-block: 1px auto;
diff --git a/src/js/background/backgroundLogic.js b/src/js/background/backgroundLogic.js
index f658cf0..3f51036 100644
--- a/src/js/background/backgroundLogic.js
+++ b/src/js/background/backgroundLogic.js
@@ -27,6 +27,7 @@ const backgroundLogic = {
 
     browser.permissions.onAdded.addListener(permissions => this.resetPermissions(permissions));
     browser.permissions.onRemoved.addListener(permissions => this.resetPermissions(permissions));
+    backgroundLogic.setSyncExclusion();
   },
 
   resetPermissions(permissions) {
@@ -483,6 +484,17 @@ const backgroundLogic = {
   cookieStoreId(userContextId) {
     if(userContextId === 0) return "firefox-default";
     return `firefox-container-${userContextId}`;
+  },
+
+  async setSyncExclusion() {    
+    // Default container sync exclude regexp to "^tmp\d+$" to prevent
+    // https://github.com/mozilla/multi-account-containers/issues/1675
+    // https://github.com/stoically/temporary-containers/issues/371
+    // for future users of the MAC + TC combination.
+    const { syncExcludeRegExp } = await browser.storage.local.get("syncExcludeRegExp");
+    if (syncExcludeRegExp === undefined) {
+      browser.storage.local.set({syncExcludeRegExp: "^tmp\\d+$"});
+    }
   }
 };
 
diff --git a/src/js/background/sync.js b/src/js/background/sync.js
index 6dfb629..fc6d875 100644
--- a/src/js/background/sync.js
+++ b/src/js/background/sync.js
@@ -128,9 +128,16 @@ const sync = {
       await sync.checkForListenersMaybeAdd();
 
       async function updateSyncIdentities() {
+        const { syncExcludeRegExp } = await browser.storage.local.get("syncExcludeRegExp");
+        const excludeRegExp = new RegExp(syncExcludeRegExp, "i");
         const identities = await browser.contextualIdentities.query({});
 
         for (const identity of identities) {
+          // skip excluded identities
+          if (identity.name.match(excludeRegExp)) {
+            continue;
+          }
+
           delete identity.colorCode;
           delete identity.iconUrl;
           identity.macAddonUUID = await identityState.lookupMACaddonUUID(identity.cookieStoreId);
diff --git a/src/js/options.js b/src/js/options.js
index 067e5dc..e1628c8 100644
--- a/src/js/options.js
+++ b/src/js/options.js
@@ -120,11 +120,13 @@ async function setupOptions() {
   const { replaceTabEnabled } = await browser.storage.local.get("replaceTabEnabled");
   const { pageActionEnabled } = await browser.storage.local.get({ pageActionEnabled: true });
   const { currentThemeId } = await browser.storage.local.get("currentThemeId");
+  const { syncExcludeRegExp } = await browser.storage.local.get("syncExcludeRegExp");
 
   document.querySelector("#syncCheck").checked = !!syncEnabled;
   document.querySelector("#replaceTabCheck").checked = !!replaceTabEnabled;
   document.querySelector("#pageActionCheck").checked = !!pageActionEnabled;
   document.querySelector("#changeTheme").selectedIndex = currentThemeId;
+  document.querySelector("#syncExcludeRegExp").value = syncExcludeRegExp || "";
   setupContainerShortcutSelects();
 }
 
@@ -178,11 +180,16 @@ async function resetPermissionsUi() {
 browser.permissions.onAdded.addListener(resetPermissionsUi);
 browser.permissions.onRemoved.addListener(resetPermissionsUi);
 
+function updateSyncExcludeRegExp(event) {
+  browser.storage.local.set({syncExcludeRegExp: event.target.value});
+}
+
 document.addEventListener("DOMContentLoaded", setupOptions);
 document.querySelector("#syncCheck").addEventListener( "change", enableDisableSync);
 document.querySelector("#replaceTabCheck").addEventListener( "change", enableDisableReplaceTab);
 document.querySelector("#pageActionCheck").addEventListener( "change", enableDisablePageAction);
 document.querySelector("#changeTheme").addEventListener( "change", changeTheme);
+document.querySelector("#syncExcludeRegExp").addEventListener( "change", updateSyncExcludeRegExp);
 document.querySelector("#containersRestoreInput").addEventListener( "change", restoreContainers);
 
 maybeShowPermissionsWarningIcon();
diff --git a/src/options.html b/src/options.html
index 80ea298..3d73d32 100644
--- a/src/options.html
+++ b/src/options.html
@@ -48,6 +48,15 @@
         </label>
         <p><em data-i18n-message-id="enableSyncDescription"></em></p>
       </div>
+      <div class="settings-group-column">
+        <label for="syncExcludeRegExp">
+          <span class="bold" data-i18n-message-id="syncExclude"></span>
+        </label>
+        <input id="syncExcludeRegExp"
+          data-i18n-attribute="placeholder"
+          data-i18n-attribute-message-id="syncExcludePlaceholder">
+        <p><em data-i18n-message-id="syncExcludeDescription"></em></p>
+      </div>
 
       <h3 data-i18n-message-id="tabBehavior"></h3>
       <div class="settings-group">