diff --git a/client/lib/i18n.js b/client/lib/i18n.js
index 5d809c17b..2e3dd10a4 100644
--- a/client/lib/i18n.js
+++ b/client/lib/i18n.js
@@ -16,6 +16,15 @@ Meteor.startup(() => {
     navigator.userLanguage,
   ].filter(Boolean);
   if (language) {
-    TAPi18n.setLanguage(language);
+    // Try with potentially complex language tag
+    if (TAPi18n.isLanguageSupported(language)) {
+      TAPi18n.setLanguage(language);
+    } else if (language.includes('-')) {
+      // Fallback to a general language
+      const [general] = language.split('-');
+      if (TAPi18n.isLanguageSupported(general)) {
+        TAPi18n.setLanguage(general);
+      }
+    }
   }
 });
diff --git a/imports/i18n/i18n.test.js b/imports/i18n/i18n.test.js
index 7805dbdc8..197a1ac19 100644
--- a/imports/i18n/i18n.test.js
+++ b/imports/i18n/i18n.test.js
@@ -78,8 +78,8 @@ describe('TAPi18n', () => {
       expect(TAPi18n.i18n.addResourceBundle.firstCall.args[2]).to.have.property('accept');
     });
 
-    it('does nothing if language is missing', async () => {
-      await expect(TAPi18n.loadLanguage('miss')).to.be.fulfilled;
+    it('throws error if language is missing', async () => {
+      await expect(TAPi18n.loadLanguage('miss')).to.be.rejectedWith('not supported');
       expect(TAPi18n.i18n.addResourceBundle).to.not.be.called;
     });
 
diff --git a/imports/i18n/tap.js b/imports/i18n/tap.js
index 2916278de..f531a23ae 100644
--- a/imports/i18n/tap.js
+++ b/imports/i18n/tap.js
@@ -32,6 +32,9 @@ export const TAPi18n = {
     // Load the current language data
     await TAPi18n.loadLanguage(DEFAULT_LANGUAGE);
   },
+  isLanguageSupported(language) {
+    return Object.values(languages).some(({ tag }) => tag === language);
+  },
   getSupportedLanguages() {
     return Object.values(languages).map(({ name, code, tag }) => ({ name, code, tag }));
   },
@@ -42,6 +45,8 @@ export const TAPi18n = {
     if (language in languages && 'load' in languages[language]) {
       const data = await languages[language].load();
       this.i18n.addResourceBundle(language, DEFAULT_NAMESPACE, data);
+    } else {
+      throw new Error(`Language ${language} is not supported`);
     }
   },
   async setLanguage(language) {