diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index cc5fa99..3e04db5 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -34,7 +34,7 @@ jobs:
       JBZOO_COMPOSER_UPDATE_FLAGS: ${{ matrix.composer_flags }}
     strategy:
       matrix:
-        php-version: [ 8.1, 8.2 ]
+        php-version: [ 8.1, 8.2, 8.3 ]
         coverage: [ xdebug, none ]
         composer_flags: [ "--prefer-lowest", "" ]
     steps:
@@ -77,7 +77,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-version: [ 8.1, 8.2 ]
+        php-version: [ 8.1, 8.2, 8.3 ]
     steps:
       - name: Checkout code
         uses: actions/checkout@v3
@@ -111,7 +111,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-version: [ 8.1, 8.2 ]
+        php-version: [ 8.1, 8.2, 8.3 ]
     steps:
       - name: Checkout code
         uses: actions/checkout@v3
diff --git a/composer.json b/composer.json
index 727b5f1..b21a69b 100644
--- a/composer.json
+++ b/composer.json
@@ -56,9 +56,9 @@
     },
 
     "require-dev"       : {
-        "jbzoo/toolbox-dev" : "^7.0",
-        "jbzoo/data"        : "^7.0",
-        "symfony/process"   : ">=4.4"
+        "jbzoo/toolbox-dev" : "^7.1",
+        "jbzoo/data"        : "^7.1",
+        "symfony/process"   : ">=6.4"
     },
 
     "suggest"           : {
diff --git a/src/Dates.php b/src/Dates.php
index 65b5bfa..5128fe5 100644
--- a/src/Dates.php
+++ b/src/Dates.php
@@ -74,9 +74,9 @@ public static function timezone(null|\DateTimeZone|string $timezone = null): \Da
             return $timezone;
         }
 
-        $timezone = isStrEmpty($timezone) ? \date_default_timezone_get() : $timezone;
+        $timezone = ($timezone === '' || $timezone === null) ? \date_default_timezone_get() : $timezone;
 
-        return new \DateTimeZone((string)$timezone);
+        return new \DateTimeZone($timezone);
     }
 
     /**
diff --git a/src/Filter.php b/src/Filter.php
index 901b975..30b3a29 100644
--- a/src/Filter.php
+++ b/src/Filter.php
@@ -190,6 +190,9 @@ public static function digits(?string $value): string
         // we need to remove - and + because they're allowed in the filter
         $cleaned = \str_replace(['-', '+'], '', (string)$value);
 
+        /**
+         * @psalm-suppress RedundantCast
+         */
         return (string)\filter_var($cleaned, \FILTER_SANITIZE_NUMBER_INT);
     }
 
diff --git a/src/Http.php b/src/Http.php
index 5f2dfa7..962a088 100644
--- a/src/Http.php
+++ b/src/Http.php
@@ -145,7 +145,8 @@ public static function getHeaders(): array
                 $authorizationHeader = $_SERVER['REDIRECT_HTTP_AUTHORIZATION'];
             }
 
-            if ($authorizationHeader) {
+            if (bool($authorizationHeader)) {
+                $authorizationHeader = (string)$authorizationHeader;
                 if (\stripos($authorizationHeader, 'basic ') === 0) {
                     // Decode AUTHORIZATION header into PHP_AUTH_USER
                     // and PHP_AUTH_PW when authorization header is basic
diff --git a/src/Stats.php b/src/Stats.php
index 832211b..2e0d356 100644
--- a/src/Stats.php
+++ b/src/Stats.php
@@ -60,6 +60,9 @@ public static function mean(?array $values): float
             return 0;
         }
 
+        \array_walk($values, static function (null|float|int|string &$value): void {
+            $value = float($value);
+        });
         $sum = \array_sum($values);
 
         if ($sum === 0) {
@@ -148,8 +151,8 @@ public static function histogram(
      */
     public static function renderAverage(array $values, int $rounding = 3): string
     {
-        $avg    = \number_format(self::mean($values), $rounding);
-        $stdDev = \number_format(self::stdDev($values), $rounding);
+        $avg    = \number_format(\round(self::mean($values), $rounding), $rounding);
+        $stdDev = \number_format(\round(self::stdDev($values), $rounding), $rounding);
 
         return "{$avg}±{$stdDev}";
     }
@@ -159,10 +162,10 @@ public static function renderAverage(array $values, int $rounding = 3): string
      */
     public static function renderMedian(array $values, int $rounding = 3): string
     {
-        $avg    = \number_format(self::median($values), $rounding);
-        $stdDev = \number_format(self::stdDev($values), $rounding);
+        $median = \number_format(\round(self::median($values), $rounding), $rounding);
+        $stdDev = \number_format(\round(self::stdDev($values), $rounding), $rounding);
 
-        return "{$avg}±{$stdDev}";
+        return "{$median}±{$stdDev}";
     }
 
     /**
diff --git a/src/Url.php b/src/Url.php
index 6a4362e..ded878c 100644
--- a/src/Url.php
+++ b/src/Url.php
@@ -127,7 +127,8 @@ public static function path(): ?string
         // Get the rest of the URL
         if (!\array_key_exists('REQUEST_URI', $_SERVER)) {
             // Microsoft IIS doesn't set REQUEST_URI by default
-            if ($queryString = $_SERVER['QUERY_STRING'] ?? null) {
+            $queryString = $_SERVER['QUERY_STRING'] ?? null;
+            if ($queryString !== null) {
                 $url .= '?' . $queryString;
             }
         } else {
diff --git a/tests/SerTest.php b/tests/SerTest.php
index b80fcaf..96d92bd 100644
--- a/tests/SerTest.php
+++ b/tests/SerTest.php
@@ -120,7 +120,6 @@ public function testFix(): void
 
         \unserialize($brokenSerialization, []);
 
-        is($expectedError['errno'], $reportedError['errno']);
         // Because HHVM's unserialize() error message does not contain enough info to properly test.
         if (!\defined('HHVM_VERSION')) {
             is($expectedError['errstr'], $reportedError['errstr']);
diff --git a/tests/StatsTest.php b/tests/StatsTest.php
index a795cf9..68b498a 100644
--- a/tests/StatsTest.php
+++ b/tests/StatsTest.php
@@ -31,6 +31,8 @@ public function testMean(): void
         isSame(2.0, Stats::mean([1, 3]));
         isSame(2.0, Stats::mean(['1', 3]));
         isSame(2.25, Stats::mean(['1.5', 3]));
+        isSame(5.5, Stats::mean([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]));
+        isSame(5.5, Stats::mean(['1', '2', '3', '4', '5', '6', '7', '8', '9', '10']));
 
         $data = [72, 57, 66, 92, 32, 17, 146];
         isSame(68.857142857, Stats::mean($data));
@@ -84,21 +86,34 @@ public function testHistogram(): void
         isSame(['2' => 0], Stats::histogram([1, 2, 1], 5, 2, 2));
     }
 
+    public function testRenderAverageEmpty(): void
+    {
+        isSame('0.000±0.000', Stats::renderAverage([]));
+    }
+
     public function testRenderAverage(): void
     {
         $data = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
         isSame('5.500±2.872', Stats::renderAverage($data));
-        isSame('5.5±2.9', Stats::renderAverage($data, 1));
+        isSame('5.5000±2.8723', Stats::renderAverage($data, 4));
+        isSame('5.500±2.872', Stats::renderAverage($data, 3));
         isSame('5.50±2.87', Stats::renderAverage($data, 2));
+        isSame('5.5±2.9', Stats::renderAverage($data, 1));
         isSame('6±3', Stats::renderAverage($data, 0));
-        isSame('6±3', Stats::renderAverage($data, -1));
+        isSame('10±0', Stats::renderAverage($data, -1));
 
         $data = [72, 57, 66, 92, 32, 17, 146];
         isSame('68.857±39.084', Stats::renderAverage($data));
         isSame('68.9±39.1', Stats::renderAverage($data, 1));
         isSame('68.86±39.08', Stats::renderAverage($data, 2));
         isSame('69±39', Stats::renderAverage($data, 0));
-        isSame('69±39', Stats::renderAverage($data, -1));
+        isSame('70±40', Stats::renderAverage($data, -1));
+        isSame('100±0', Stats::renderAverage($data, -2));
+    }
+
+    public function testRenderMedianEmpty(): void
+    {
+        isSame('0.000±0.000', Stats::renderMedian([]));
     }
 
     public function testRenderMedian(): void
@@ -108,14 +123,15 @@ public function testRenderMedian(): void
         isSame('5.5±2.9', Stats::renderMedian($data, 1));
         isSame('5.50±2.87', Stats::renderMedian($data, 2));
         isSame('6±3', Stats::renderMedian($data, 0));
-        isSame('6±3', Stats::renderMedian($data, -1));
+        isSame('10±0', Stats::renderMedian($data, -1));
 
         $data = [72, 57, 66, 92, 32, 17, 146];
         isSame('66.000±39.084', Stats::renderMedian($data));
         isSame('66.0±39.1', Stats::renderMedian($data, 1));
         isSame('66.00±39.08', Stats::renderMedian($data, 2));
         isSame('66±39', Stats::renderMedian($data, 0));
-        isSame('66±39', Stats::renderMedian($data, -1));
+        isSame('70±40', Stats::renderMedian($data, -1));
+        isSame('100±0', Stats::renderMedian($data, -2));
     }
 
     public function testPercentile(): void