diff --git a/apps/locale/locales.js b/apps/locale/locales.js
index 15d9b9c90..7e4105f3d 100644
--- a/apps/locale/locales.js
+++ b/apps/locale/locales.js
@@ -753,4 +753,27 @@ var locales = {
     day: "ראשון,שני,שלישי,רביעי,חמישי,שישי,שבת",
     trans: { yes: "כן", Yes: "כן", no: "לא", No: "לא", ok: "אישור", on: "פעיל", off: "כבוי" }
   }*/
+ /**
+  * These test strings are designed to be as wide and tall as real locale strings can be.
+  * All apps should be able to display them properly, to ensure that they work with all locales.
+  * To make the strings as long as possible, wide characters like "w" and "m" is used,
+  * and to make them taller, "k" and "g" are used together. 
+  */
+ "test": {
+    lang: "test",
+    icon: "🐛",
+    notes: "Produces the longest possible output. Useful for testing.",
+    decimal_point: ",",
+    thousands_sep: ",",
+    speed: "km/h",
+    distance: { 0: "kmi", 1: "kmi" },
+    temperature: "°C",
+    ampm: { 0: "dop", 1: "odp" },
+    timePattern: { 0: "%HHh%MM:%SS", 1: "%HHh%MM" },
+    datePattern: { 0: "%b, %d, %Y", 1: "%d. %m %Y" },
+    abmonth: Array(12).fill("mgmk").join(","),
+    month: Array(12).fill("megmmaskuum").join(","),
+    abday: Array(7).fill("mgmk").join(","),
+    day: Array(7).fill("megmavammkkom").join(","),
+  },
 };
diff --git a/apps/locale/sanitycheck.js b/apps/locale/sanitycheck.js
index 192fa338a..06c7ad3d6 100644
--- a/apps/locale/sanitycheck.js
+++ b/apps/locale/sanitycheck.js
@@ -91,7 +91,7 @@ function checkLocale(locale, {speedUnits, distanceUnits, codePages, CODEPAGE_CON
 	const speeds = Object.keys(speedUnits);
 	const distances = Object.keys(distanceUnits);
 
-	checkLength("lang", locale.lang, 5, undefined);
+	checkLength("lang", locale.lang, 4, undefined);
 	checkLength("decimal point", locale.decimal_point, 1, 1);
 	checkLength("thousands separator", locale.thousands_sep, 1, 1);
 	checkLength("speed", locale.speed, 2, 4);
diff --git a/bin/sanitycheck.js b/bin/sanitycheck.js
index eceb0d491..82856b639 100755
--- a/bin/sanitycheck.js
+++ b/bin/sanitycheck.js
@@ -109,7 +109,9 @@ var KNOWN_WARNINGS = [
   `In locale it_CH, long time format might not work in some apps if it is not "%HH:%MM:%SS"`,
   `In locale it_IT, long time format might not work in some apps if it is not "%HH:%MM:%SS"`,
   `In locale wae_CH, long time format might not work in some apps if it is not "%HH:%MM:%SS"`,
+  `In locale test, long time format might not work in some apps if it is not "%HH:%MM:%SS"`,
   `In locale wae_CH, short time format might not work in some apps if it is not "%HH:%MM"`,
+  `In locale test, short time format might not work in some apps if it is not "%HH:%MM"`,
 ];
 
 var apps = [];