diff --git a/.github/workflows/static.yml b/.github/workflows/static.yml
index 1b48889..e02e209 100644
--- a/.github/workflows/static.yml
+++ b/.github/workflows/static.yml
@@ -17,7 +17,7 @@ jobs:
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
         with:
-          php-version: '7.4'
+          php-version: '8.0'
           tools: composer:v2
           coverage: none
 
diff --git a/composer.json b/composer.json
index b05988c..5e22f18 100644
--- a/composer.json
+++ b/composer.json
@@ -27,7 +27,7 @@
         "guzzlehttp/psr7": "^2.0",
         "php-http/discovery": "^1.14",
         "phpunit/phpunit": "^9.5 || ^10.0",
-        "psalm/phar": "4.8.1",
+        "psalm/phar": "4.15.0",
         "psr/http-factory": "^1.0.1",
         "psr/http-message": "^1.0.1",
         "squizlabs/php_codesniffer": "3.6.0"
diff --git a/src/Utilities/TimeFormatter.php b/src/Utilities/TimeFormatter.php
index f6afa67..0bee483 100644
--- a/src/Utilities/TimeFormatter.php
+++ b/src/Utilities/TimeFormatter.php
@@ -16,6 +16,9 @@ final class TimeFormatter
     private const TIME_FORMAT = 'Y-m-d\TH:i:s\Z';
     private const TIME_ZONE = 'UTC';
 
+    private const RFC3339_FORMAT = 'Y-m-d\TH:i:sP';
+    private const RFC3339_EXTENDED_FORMAT = 'Y-m-d\TH:i:s.uP';
+
     public static function encode(?DateTimeImmutable $time): ?string
     {
         if ($time === null) {
@@ -31,7 +34,11 @@ public static function decode(?string $time): ?DateTimeImmutable
             return null;
         }
 
-        $decoded = DateTimeImmutable::createFromFormat(self::TIME_FORMAT, $time, new DateTimeZone(self::TIME_ZONE));
+        $decoded = DateTimeImmutable::createFromFormat(
+            \str_contains($time, '.') ? self::RFC3339_EXTENDED_FORMAT : self::RFC3339_FORMAT,
+            \strtoupper($time),
+            new DateTimeZone(self::TIME_ZONE)
+        );
 
         if ($decoded === false) {
             throw new ValueError(
diff --git a/src/V1/CloudEventTrait.php b/src/V1/CloudEventTrait.php
index 77bf4a9..23d11cd 100644
--- a/src/V1/CloudEventTrait.php
+++ b/src/V1/CloudEventTrait.php
@@ -273,10 +273,6 @@ private function setExtension(string $attribute, $value): self
             );
         }
 
-        /**
-         * @psalm-suppress UndefinedFunction
-         * @var string
-         */
         $type = \get_debug_type($value);
         $types = ['bool', 'int', 'string', 'null'];
 
diff --git a/tests/Unit/Utilities/TimeFormatterTest.php b/tests/Unit/Utilities/TimeFormatterTest.php
index b648911..be3514e 100644
--- a/tests/Unit/Utilities/TimeFormatterTest.php
+++ b/tests/Unit/Utilities/TimeFormatterTest.php
@@ -19,11 +19,49 @@ public function testEncode(): void
         );
     }
 
-    public function testDecode(): void
+    public function providesDecodeCases(): array
+    {
+        return [
+            // UTC
+            ['2018-04-05T17:31:00Z', '2018-04-05T17:31:00Z'],
+            ['1985-04-12T23:20:50.100000Z', '1985-04-12T23:20:50.1Z'],
+            ['1985-04-12T23:20:50.100000Z', '1985-04-12T23:20:50.10Z'],
+            ['1985-04-12T23:20:50.100000Z', '1985-04-12T23:20:50.100Z'],
+            ['1985-04-12T23:20:50.120000Z', '1985-04-12T23:20:50.12Z'],
+            ['1985-04-12T23:20:50.120000Z', '1985-04-12T23:20:50.120Z'],
+            ['1985-04-12T23:20:50.123000Z', '1985-04-12T23:20:50.123Z'],
+            ['1985-04-12T23:20:50.123000Z', '1985-04-12T23:20:50.12300Z'],
+            ['1985-04-12T23:20:50.123400Z', '1985-04-12T23:20:50.1234Z'],
+            ['1985-04-12T23:20:50.123400Z', '1985-04-12T23:20:50.123400Z'],
+            ['1985-04-12T23:20:50.123450Z', '1985-04-12T23:20:50.12345Z'],
+            ['1985-04-12T23:20:50.123450Z', '1985-04-12T23:20:50.123450Z'],
+            ['1985-04-12T23:20:50.123456Z', '1985-04-12T23:20:50.123456Z'],
+
+            // +01:00
+            ['2018-04-05T16:31:00Z', '2018-04-05T17:31:00+01:00'],
+            ['1985-04-12T22:20:50.100000Z', '1985-04-12T23:20:50.1+01:00'],
+            ['1985-04-12T22:20:50.100000Z', '1985-04-12T23:20:50.10+01:00'],
+            ['1985-04-12T22:20:50.100000Z', '1985-04-12T23:20:50.100+01:00'],
+            ['1985-04-12T22:20:50.120000Z', '1985-04-12T23:20:50.12+01:00'],
+            ['1985-04-12T22:20:50.120000Z', '1985-04-12T23:20:50.120+01:00'],
+            ['1985-04-12T22:20:50.123000Z', '1985-04-12T23:20:50.123+01:00'],
+            ['1985-04-12T22:20:50.123000Z', '1985-04-12T23:20:50.12300+01:00'],
+            ['1985-04-12T22:20:50.123400Z', '1985-04-12T23:20:50.1234+01:00'],
+            ['1985-04-12T22:20:50.123400Z', '1985-04-12T23:20:50.123400+01:00'],
+            ['1985-04-12T22:20:50.123450Z', '1985-04-12T23:20:50.12345+01:00'],
+            ['1985-04-12T22:20:50.123450Z', '1985-04-12T23:20:50.123450+01:00'],
+            ['1985-04-12T22:20:50.123456Z', '1985-04-12T23:20:50.123456+01:00'],
+        ];
+    }
+
+    /**
+     * @dataProvider providesDecodeCases
+     */
+    public function testDecode(string $expected, string $input): void
     {
         self::assertEquals(
-            new DateTimeImmutable('2018-04-05T17:31:00Z'),
-            TimeFormatter::decode('2018-04-05T17:31:00Z')
+            new DateTimeImmutable($expected),
+            TimeFormatter::decode($input)
         );
     }