diff --git a/CHANGELOG.md b/CHANGELOG.md
index cf906b0..8a99a2b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -41,6 +41,7 @@ There's a change in flash messages handling, please see #391
 - Enh: added `AdminController` REST controller (MatteoF96)
 - Enh: added method `setUser` for LoginForm model (liviuk2)
 - Enh: user model emailTrim validator only if not empty #486 (liviuk2)
+- Fix #461: TimeZoneHelper: don't use floats for columns that could be array keys (maxxer)
 
 ## 1.5.1 April 5, 2020
 
diff --git a/src/User/Helper/TimezoneHelper.php b/src/User/Helper/TimezoneHelper.php
index aba5f17..7f8e9b7 100644
--- a/src/User/Helper/TimezoneHelper.php
+++ b/src/User/Helper/TimezoneHelper.php
@@ -36,7 +36,8 @@ class TimezoneHelper
             $timeZones[] = [
                 'timezone' => $timeZone,
                 'name' => "{$timeZone} (UTC " . ($offset > 0 ? '+' : '') . "{$offset})",
-                'offset' => $offset,
+                // As of PHP 8.1 array keys cannot be float. Offset is used for sorting only
+                'offset' => $offset * 100,
             ];
         }
 
diff --git a/src/User/Validator/TimeZoneValidator.php b/src/User/Validator/TimeZoneValidator.php
index 387ac83..8bb808f 100644
--- a/src/User/Validator/TimeZoneValidator.php
+++ b/src/User/Validator/TimeZoneValidator.php
@@ -12,6 +12,7 @@
 namespace Da\User\Validator;
 
 use Da\User\Contracts\ValidatorInterface;
+use DateTimeZone;
 
 class TimeZoneValidator implements ValidatorInterface
 {
@@ -24,6 +25,6 @@ class TimeZoneValidator implements ValidatorInterface
 
     public function validate()
     {
-        return in_array($this->timezone, timezone_identifiers_list(), false);
+        return in_array($this->timezone, DateTimeZone::listIdentifiers(), false);
     }
 }
diff --git a/tests/unit/TimeZoneTest.php b/tests/unit/TimeZoneTest.php
new file mode 100644
index 0000000..b425abe
--- /dev/null
+++ b/tests/unit/TimeZoneTest.php
@@ -0,0 +1,26 @@
+<?php
+
+use Da\User\Helper\TimezoneHelper;
+use Da\User\Validator\TimeZoneValidator;
+use yii\helpers\ArrayHelper;
+
+/**
+ * Testing the Timezone generator functions
+ */
+class TimeZoneTest extends \Codeception\Test\Unit
+{
+    // Basic test to check the function works
+    public function testTimezoneHelper()
+    {
+        $alltz = (new TimezoneHelper)->getAll();
+        $this->assertTrue(in_array("Europe/Rome", ArrayHelper::getColumn($alltz, "timezone")));
+        $this->assertTrue(in_array("0100", ArrayHelper::getColumn($alltz, "offset")));
+    }
+
+    // Test with minPasswordRequirements equal to an empty array (= password without requirements)
+    public function testTimeZoneValidator()
+    {
+        $v = Yii::createObject(TimeZoneValidator::class, ["Europe/Rome"]);
+        $this->assertTrue($v->validate());
+    }
+}