diff --git a/src/Countries/Australia.php b/src/Countries/Australia.php
index 42511f516..ac572f858 100644
--- a/src/Countries/Australia.php
+++ b/src/Countries/Australia.php
@@ -19,7 +19,7 @@ public function countryCode(): string
     protected function allHolidays(int $year): array
     {
         return array_merge([
-            'New Year\'s Day' => '01-01',
+            "New Year's Day" => '01-01',
             'Australia Day' => '01-26',
             'Anzac Day' => '04-25',
             'Christmas Day' => '12-25',
@@ -42,15 +42,13 @@ protected function variableHolidays(int $year): array
                     'Easter Saturday' => $easter->subDay(),
                     'Easter Sunday' => $easter,
                     'Reconciliation Day' => CarbonImmutable::create($year, 5, 27)->modify("monday"),
-                    'King\'s Birthday' => $year >= 2023 ? CarbonImmutable::parse("second monday of june {$year}") : null,
-                    'Queen\'s Birthday' => $year < 2023 ? CarbonImmutable::parse("second monday of june {$year}") : null,
+                    $this->sovereignBirthdayKey($year) => CarbonImmutable::parse("second monday of june {$year}"),
                     'Labour Day' => CarbonImmutable::parse("first monday of october {$year}"),
                 ],
                 'nsw' => [
                     'Easter Saturday' => $easter->subDay(),
                     'Easter Sunday' => $easter,
-                    'King\'s Birthday' => $year >= 2023 ? CarbonImmutable::parse("second monday of june {$year}") : null,
-                    'Queen\'s Birthday' => $year < 2023 ? CarbonImmutable::parse("second monday of june {$year}") : null,
+                    $this->sovereignBirthdayKey($year) => CarbonImmutable::parse("second monday of june {$year}"),
                     'Labour Day' => CarbonImmutable::parse("first monday of october {$year}"),
                 ],
                 'nt' => [
@@ -62,29 +60,25 @@ protected function variableHolidays(int $year): array
                     'The day after Good Friday' => $easter->subDay(),
                     'Easter Sunday' => $easter,
                     'Labour Day' => CarbonImmutable::parse("first monday of may {$year}"),
-                    'King\'s Birthday' => $year >= 2023 ? CarbonImmutable::parse("first monday of october {$year}") : null,
-                    'Queen\'s Birthday' => $year < 2023 ? CarbonImmutable::parse("first monday of october {$year}") : null,
+                    $this->sovereignBirthdayKey($year) => CarbonImmutable::parse("first monday of october {$year}"),
                 ],
                 'sa' => [
                     'Adelaide Cup Day' => $year < 2006
                         ? CarbonImmutable::parse("third monday of may {$year}")
                         : CarbonImmutable::parse("second monday of march {$year}"),
                     'The day after Good Friday' => $easter->subDay(),
-                    'King\'s Birthday' => $year >= 2023 ? CarbonImmutable::parse("second monday of june {$year}") : null,
-                    'Queen\'s Birthday' => $year < 2023 ? CarbonImmutable::parse("second monday of june {$year}") : null,
+                    $this->sovereignBirthdayKey($year) => CarbonImmutable::parse("second monday of june {$year}"),
                     'Labour Day' => CarbonImmutable::parse("first monday of october {$year}"),
                 ],
                 'tas' => [
                     'Eight Hours Day' => CarbonImmutable::parse("second monday of march {$year}"),
-                    'King\'s Birthday' => $year >= 2023 ? CarbonImmutable::parse("second monday of june {$year}") : null,
-                    'Queen\'s Birthday' => $year < 2023 ? CarbonImmutable::parse("second monday of june {$year}") : null,
+                    $this->sovereignBirthdayKey($year) => CarbonImmutable::parse("second monday of june {$year}"),
                 ],
                 'vic' => [
                     'Labour Day' => CarbonImmutable::parse("second monday of march {$year}"),
                     'Saturday before Easter Sunday' => $easter->subDay(),
                     'Easter Sunday' => $easter,
-                    'King\'s Birthday' => $year >= 2023 ? CarbonImmutable::parse("second monday of june {$year}") : null,
-                    'Queen\'s Birthday' => $year < 2023 ? CarbonImmutable::parse("second monday of june {$year}") : null,
+                    $this->sovereignBirthdayKey($year) => CarbonImmutable::parse("second monday of june {$year}"),
                     'Friday before AFL Grand Final' => $this->fridayBeforeAflGrandFinal($year),
                     'Melbourne Cup' => CarbonImmutable::parse("first tuesday of november {$year}"),
                 ],
@@ -92,9 +86,7 @@ protected function variableHolidays(int $year): array
                     'Labour Day' => CarbonImmutable::parse("first monday of march {$year}"),
                     'Easter Sunday' => $easter,
                     'Western Australia Day' => CarbonImmutable::parse("first monday of june {$year}"),
-                    // https://www.abc.net.au/news/2022-09-22/queens-birthday-public-holiday-becomes-kings-birthday/101453408
-                    'King\'s Birthday' => $year >= 2022 ? CarbonImmutable::parse("last monday of september {$year}") : null,
-                    'Queen\'s Birthday' => $year < 2022 ? CarbonImmutable::parse("last monday of september {$year}") : null,
+                    $this->sovereignBirthdayKey($year) => CarbonImmutable::parse("last monday of september {$year}"),
                 ],
                 default => [],
             }),
@@ -116,4 +108,12 @@ protected function fridayBeforeAflGrandFinal(int $year): ?CarbonImmutable
             default => CarbonImmutable::parse("last friday of september {$year}"),
         };
     }
+
+    protected function sovereignBirthdayKey(int $year): string
+    {
+        // https://www.abc.net.au/news/2022-09-22/queens-birthday-public-holiday-becomes-kings-birthday/101453408
+        $changeYear = $this->region === 'wa' ? 2022 : 2023;
+
+        return $year >= $changeYear ? "King's Birthday" : "Queen's Birthday";
+    }
 }
diff --git a/tests/Countries/AustraliaTest.php b/tests/Countries/AustraliaTest.php
index 27f8a8b76..e274579df 100644
--- a/tests/Countries/AustraliaTest.php
+++ b/tests/Countries/AustraliaTest.php
@@ -69,27 +69,27 @@
         ->toBeNull();
 });
 
-it('returns queen\'s birthday before her death', function () {
+it("returns queen's birthday before her death", function () {
     CarbonImmutable::setTestNowAndTimezone('2021-01-22', 'Australia/Perth');
 
     $holidays = Holidays::for(Australia::make('wa'))->get();
 
-    expect(findDate($holidays, 'Queen\'s Birthday'))
+    expect(findDate($holidays, "Queen's Birthday"))
         ->toEqual(CarbonImmutable::create(2021, 9, 27));
 
-    expect(findDate($holidays, 'King\'s Birthday'))
+    expect(findDate($holidays, "King's Birthday"))
         ->toBeNull();
 });
 
-it('returns king\'s birthday after her death', function () {
+it("returns king's birthday after her death", function () {
     CarbonImmutable::setTestNowAndTimezone('2022-01-22', 'Australia/Perth');
 
     $holidays = Holidays::for(Australia::make('wa'))->get();
 
-    expect(findDate($holidays, 'Queen\'s Birthday'))
+    expect(findDate($holidays, "Queen's Birthday"))
         ->toBeNull();
 
-    expect(findDate($holidays, 'King\'s Birthday'))
+    expect(findDate($holidays, "King's Birthday"))
         ->toEqual(CarbonImmutable::create(2022, 9, 26));
 });