diff --git a/packages/client/src/Client/Internal/Connection/LazyConnection.php b/packages/client/src/Client/Internal/Connection/LazyConnection.php
index 8428691..7c89a4a 100644
--- a/packages/client/src/Client/Internal/Connection/LazyConnection.php
+++ b/packages/client/src/Client/Internal/Connection/LazyConnection.php
@@ -47,11 +47,38 @@ public function close(Cancellation $cancellation = new NullCancellation()): void
         $future = $this->future;
         $this->future = null;
 
-        $future?->await($cancellation)->close($cancellation);
+        if ($future === null) {
+            return;
+        }
+
+        try {
+            $connection = $future->await($cancellation);
+        } catch (\Throwable $e) {
+            if ($future->isComplete()) {
+                // The connection was never established: there is nothing to close.
+                return;
+            }
+
+            throw $e;
+        }
+
+        $connection->close($cancellation);
     }
 
     private function createConnection(Cancellation $cancellation): Connection
     {
-        return ($this->future ??= async($this->factory))->await($cancellation);
+        $future = $this->future ??= async($this->factory);
+
+        try {
+            return $future->await($cancellation);
+        } catch (\Throwable $e) {
+            // Forget a failed attempt so the next call retries it. A caller that merely
+            // stopped waiting (cancellation) leaves the attempt running for the others.
+            if ($future->isComplete() && $this->future === $future) {
+                $this->future = null;
+            }
+
+            throw $e;
+        }
     }
 }
diff --git a/tests/Client/Internal/Connection/LazyConnectionTest.php b/tests/Client/Internal/Connection/LazyConnectionTest.php
new file mode 100644
index 0000000..81fd44a
--- /dev/null
+++ b/tests/Client/Internal/Connection/LazyConnectionTest.php
@@ -0,0 +1,158 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Thesis\Grpc\Client\Internal\Connection;
+
+use Amp\Cancellation;
+use Amp\CancelledException;
+use Amp\DeferredCancellation;
+use Amp\NullCancellation;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\TestCase;
+use Thesis\Grpc\Client\Internal\Connection;
+use Thesis\Grpc\Client\Invoke;
+use Thesis\Grpc\Client\PickContext;
+use Thesis\Grpc\Metadata;
+use Thesis\Grpc\RpcType;
+use function Amp\async;
+use function Amp\delay;
+use function Amp\Future\await;
+
+#[CoversClass(LazyConnection::class)]
+final class LazyConnectionTest extends TestCase
+{
+    public function testCreatesTheConnectionOnce(): void
+    {
+        $created = 0;
+        $connection = new LazyConnection(static function () use (&$created): Connection {
+            ++$created;
+
+            return new StubConnection();
+        });
+
+        self::createStream($connection);
+        self::createStream($connection);
+
+        self::assertSame(1, $created);
+    }
+
+    public function testConcurrentCallersShareOneAttempt(): void
+    {
+        $created = 0;
+        $connection = new LazyConnection(static function () use (&$created): Connection {
+            ++$created;
+            delay(0.01);
+
+            return new StubConnection();
+        });
+
+        await([
+            async(self::createStream(...), $connection),
+            async(self::createStream(...), $connection),
+        ]);
+
+        self::assertSame(1, $created);
+    }
+
+    public function testRetriesAfterAFailedAttempt(): void
+    {
+        $attempts = 0;
+        $connection = new LazyConnection(static function () use (&$attempts): Connection {
+            if (++$attempts === 1) {
+                throw new \RuntimeException('Resolution failed.');
+            }
+
+            return new StubConnection();
+        });
+
+        try {
+            self::createStream($connection);
+            self::fail('Expected the first attempt to fail.');
+        } catch (\RuntimeException $e) {
+            self::assertSame('Resolution failed.', $e->getMessage());
+        }
+
+        self::createStream($connection);
+
+        self::assertSame(2, $attempts);
+    }
+
+    public function testCancelledWaitDoesNotAbandonTheAttempt(): void
+    {
+        $attempts = 0;
+        $connection = new LazyConnection(static function () use (&$attempts): Connection {
+            ++$attempts;
+            delay(0.02);
+
+            return new StubConnection();
+        });
+
+        $cancellation = new DeferredCancellation();
+        $waiter = async(self::createStream(...), $connection, $cancellation->getCancellation());
+        delay(0.005);
+        $cancellation->cancel();
+
+        try {
+            $waiter->await();
+            self::fail('Expected the wait to be cancelled.');
+        } catch (CancelledException) {
+        }
+
+        self::createStream($connection);
+
+        self::assertSame(1, $attempts);
+    }
+
+    public function testClosesTheCreatedConnection(): void
+    {
+        $stub = new StubConnection();
+        $connection = new LazyConnection(static fn(): Connection => $stub);
+
+        self::createStream($connection);
+        $connection->close();
+
+        self::assertTrue($stub->closed);
+    }
+
+    public function testCloseIgnoresAFailedAttempt(): void
+    {
+        $connection = new LazyConnection(static function (): Connection {
+            delay(0.01);
+
+            throw new \RuntimeException('Resolution failed.');
+        });
+
+        $caller = async(self::createStream(...), $connection);
+        delay(0.001);
+
+        $connection->close();
+
+        $this->expectException(\RuntimeException::class);
+        $caller->await();
+    }
+
+    public function testCloseBeforeFirstUseIsANoOp(): void
+    {
+        $created = 0;
+        $connection = new LazyConnection(static function () use (&$created): Connection {
+            ++$created;
+
+            return new StubConnection();
+        });
+
+        $connection->close();
+
+        self::assertSame(0, $created);
+    }
+
+    private static function createStream(LazyConnection $connection, Cancellation $cancellation = new NullCancellation()): void
+    {
+        $connection->createStream(
+            new Invoke('/svc/Method', \stdClass::class, RpcType::Unary),
+            new Metadata(),
+            $cancellation,
+            new PickContext('/svc/Method', new Metadata()),
+        );
+    }
+}
diff --git a/tests/Client/Internal/Connection/StubConnection.php b/tests/Client/Internal/Connection/StubConnection.php
new file mode 100644
index 0000000..8023f81
--- /dev/null
+++ b/tests/Client/Internal/Connection/StubConnection.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Thesis\Grpc\Client\Internal\Connection;
+
+use Amp\Cancellation;
+use Amp\NullCancellation;
+use Thesis\Grpc\Client\Internal\Connection;
+use Thesis\Grpc\Client\Invoke;
+use Thesis\Grpc\Client\PickContext;
+use Thesis\Grpc\ClientStream;
+use Thesis\Grpc\Metadata;
+
+final class StubConnection implements Connection
+{
+    public bool $closed = false;
+
+    /**
+     * @template In of object
+     * @template Out of object
+     * @param Invoke<In, Out> $invoke
+     * @return StubStream<In, Out>
+     */
+    #[\Override]
+    public function createStream(Invoke $invoke, Metadata $md, Cancellation $cancellation, PickContext $pick): ClientStream
+    {
+        /** @var StubStream<In, Out> */
+        return new StubStream();
+    }
+
+    #[\Override]
+    public function close(Cancellation $cancellation = new NullCancellation()): void
+    {
+        $this->closed = true;
+    }
+}
diff --git a/tests/Client/Internal/Connection/StubStream.php b/tests/Client/Internal/Connection/StubStream.php
new file mode 100644
index 0000000..3013cb2
--- /dev/null
+++ b/tests/Client/Internal/Connection/StubStream.php
@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Thesis\Grpc\Client\Internal\Connection;
+
+use Amp\Cancellation;
+use Amp\NullCancellation;
+use Thesis\Grpc\ClientStream;
+use Thesis\Grpc\Metadata;
+
+/**
+ * A stream that never carries messages: the connection tests only need one to exist.
+ *
+ * @template In of object
+ * @template-covariant Out of object
+ * @implements ClientStream<In, Out>
+ */
+final readonly class StubStream implements ClientStream
+{
+    #[\Override]
+    public function send(object $message): void {}
+
+    #[\Override]
+    public function receive(): object
+    {
+        throw new \LogicException('The stub stream carries no messages.');
+    }
+
+    #[\Override]
+    public function headers(): Metadata
+    {
+        return new Metadata();
+    }
+
+    #[\Override]
+    public function trailers(Cancellation $cancellation = new NullCancellation()): Metadata
+    {
+        return new Metadata();
+    }
+
+    #[\Override]
+    public function close(): void {}
+
+    #[\Override]
+    public function getIterator(): \Traversable
+    {
+        yield from [];
+    }
+}