diff --git a/packages/grpc/src/Metadata/Status.php b/packages/grpc/src/Metadata/Status.php
index f3cc260..7f3720d 100644
--- a/packages/grpc/src/Metadata/Status.php
+++ b/packages/grpc/src/Metadata/Status.php
@@ -27,7 +27,11 @@ public function append(Metadata $md): Metadata
     {
         $md = $md
             ->replace(self::STATUS_HEADER, (string) $this->code->value)
-            ->replace(self::MESSAGE_HEADER, $this->message ?? '');
+            ->replace(self::MESSAGE_HEADER, (string) preg_replace_callback(
+                '/[^\x20-\x24\x26-\x7e]/',
+                static fn(array $byte): string => \sprintf('%%%02X', \ord($byte[0])),
+                $this->message ?? '',
+            ));
 
         if ($this->details !== null && $this->details !== '') {
             $md = $md->replace(self::DETAILS_HEADER, $this->details);
@@ -46,7 +50,7 @@ function parseStatus(Metadata $md): Status
 
     return new Status(
         $code,
-        $md->value(Status::MESSAGE_HEADER),
+        ($message = $md->value(Status::MESSAGE_HEADER)) !== null ? rawurldecode($message) : null,
         $md->value(Status::DETAILS_HEADER),
     );
 }
diff --git a/packages/server/src/Server/Internal/Http2/ServerRequestHandler.php b/packages/server/src/Server/Internal/Http2/ServerRequestHandler.php
index 7e3500e..ed41275 100644
--- a/packages/server/src/Server/Internal/Http2/ServerRequestHandler.php
+++ b/packages/server/src/Server/Internal/Http2/ServerRequestHandler.php
@@ -115,10 +115,9 @@ public function handleRequest(Request $request): Response
             return new Response(
                 status: HttpStatus::OK,
                 headers: $headers->kv,
-                trailers: new Trailers(Future::complete([
-                    Metadata\Status::STATUS_HEADER => (string) Rpc\Code::UNIMPLEMENTED->value,
-                    Metadata\Status::MESSAGE_HEADER => $e->getMessage(),
-                ])),
+                trailers: new Trailers(Future::complete(
+                    new Metadata()->withKey(new Metadata\Status(Rpc\Code::UNIMPLEMENTED, $e->getMessage()))->kv,
+                )),
             );
         }
 
diff --git a/tests/Metadata/StatusTest.php b/tests/Metadata/StatusTest.php
new file mode 100644
index 0000000..3900c24
--- /dev/null
+++ b/tests/Metadata/StatusTest.php
@@ -0,0 +1,89 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Thesis\Grpc\Metadata;
+
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\CoversFunction;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+use Thesis\Google\Rpc;
+use Thesis\Grpc\Metadata;
+
+#[CoversClass(Status::class)]
+#[CoversFunction('Thesis\Grpc\Metadata\parseStatus')]
+final class StatusTest extends TestCase
+{
+    #[DataProvider('provideMessageCases')]
+    public function testMessage(string $message, string $headerValue): void
+    {
+        $md = new Metadata()->withKey(new Status(Rpc\Code::INTERNAL, $message));
+
+        self::assertSame($headerValue, $md->value(Status::MESSAGE_HEADER));
+        self::assertSame($message, parseStatus($md)->message);
+    }
+
+    /**
+     * @return iterable<array-key, array{string, string}>
+     */
+    public static function provideMessageCases(): iterable
+    {
+        yield 'ascii' => [
+            'Unknown method Ping for service echos.api.v1.EchoService: [{}] ~!',
+            'Unknown method Ping for service echos.api.v1.EchoService: [{}] ~!',
+        ];
+
+        yield 'percent' => [
+            '100%',
+            '100%25',
+        ];
+
+        yield 'range boundaries' => [
+            " $%&~\x7f",
+            ' $%25&~%7F',
+        ];
+
+        yield 'special status message' => [
+            "\t\ntest with whitespace\r\nand Unicode BMP ☺ and non-BMP 😈\t\n",
+            '%09%0Atest with whitespace%0D%0Aand Unicode BMP %E2%98%BA and non-BMP %F0%9F%98%88%09%0A',
+        ];
+    }
+
+    #[DataProvider('provideParseMessageCases')]
+    public function testParseMessage(string $headerValue, string $message): void
+    {
+        self::assertSame($message, parseStatus(new Metadata()->with(Status::MESSAGE_HEADER, $headerValue))->message);
+    }
+
+    /**
+     * @return iterable<array-key, array{string, string}>
+     */
+    public static function provideParseMessageCases(): iterable
+    {
+        yield 'lowercase hex' => [
+            '%e2%98%ba',
+            '☺',
+        ];
+
+        yield 'invalid escape' => [
+            '%zz',
+            '%zz',
+        ];
+
+        yield 'trailing percent' => [
+            'done 100%',
+            'done 100%',
+        ];
+
+        yield 'plus is not a space' => [
+            'a+b',
+            'a+b',
+        ];
+    }
+
+    public function testMissingMessage(): void
+    {
+        self::assertNull(parseStatus(new Metadata())->message);
+    }
+}
diff --git a/tests/NotImplementedTest.php b/tests/NotImplementedTest.php
index a25b81d..bf7ce12 100644
--- a/tests/NotImplementedTest.php
+++ b/tests/NotImplementedTest.php
@@ -63,4 +63,13 @@ public function testMethodNotImplemented(): void
         $this->expectExceptionMessage('A grpc error with status code "UNIMPLEMENTED" and message "Unknown method Ping for service echos.api.v1.EchoService" occurred');
         $client->invoke(new EchoRequest(), new Invoke('/echos.api.v1.EchoService/Ping', EchoResponse::class, RpcType::Unary));
     }
+
+    public function testMethodNotImplementedMessageIsPercentEncoded(): void
+    {
+        $client = new Client\Builder()->build();
+
+        // The client URI layer encodes "%" in the path before it reaches the server, so the server reports the method as "100%25".
+        $this->expectExceptionMessage('A grpc error with status code "UNIMPLEMENTED" and message "Unknown method 100%25 for service echos.api.v1.EchoService" occurred');
+        $client->invoke(new EchoRequest(), new Invoke('/echos.api.v1.EchoService/100%', EchoResponse::class, RpcType::Unary));
+    }
 }
diff --git a/tests/UnaryTest.php b/tests/UnaryTest.php
index 5b3dafc..fc02d94 100644
--- a/tests/UnaryTest.php
+++ b/tests/UnaryTest.php
@@ -119,6 +119,28 @@ public function testServerHandlerException(): void
 
         self::fail('Client::echo() above should be throw an exception');
     }
+
+    public function testSpecialStatusMessage(): void
+    {
+        $client = new EchoServiceClient(
+            new Client\Builder()
+            ->withUnaryInterceptors(new AuthorizationClientInterceptor('secret'))
+            ->build(),
+        );
+
+        $message = "\t\ntest with whitespace\r\nand Unicode BMP ☺ and non-BMP 😈\t\n";
+
+        try {
+            $client->echo(new EchoRequest($message), new Metadata()->with('server-status-message', '1'));
+        } catch (InvokeError $e) {
+            self::assertSame(Code::UNKNOWN, $e->statusCode);
+            self::assertSame($message, $e->statusMessage);
+
+            return;
+        }
+
+        self::fail('Client::echo() above should be throw an exception');
+    }
 }
 
 final readonly class UnaryEchoServer implements EchoServiceServer
@@ -138,6 +160,10 @@ public function echo(
             ]);
         }
 
+        if ($md->value('server-status-message') === '1') {
+            throw new InvokeError(Code::UNKNOWN, $request->sentence);
+        }
+
         $sentence = $md->value('server-sentence') ?? $request->sentence;
 
         return new EchoResponse($sentence);