diff --git a/src/Models/LetsEncryptCertificate.php b/src/Models/LetsEncryptCertificate.php
index 966b068..7161940 100644
--- a/src/Models/LetsEncryptCertificate.php
+++ b/src/Models/LetsEncryptCertificate.php
@@ -61,11 +61,11 @@ public function getHasExpiredAttribute(): bool
 
     public function renew(): PendingDispatch
     {
-        return LetsEncrypt::renew($this->domain);
+        return LetsEncrypt::renew($this);
     }
 
     public function renewNow(): self
     {
-        return LetsEncrypt::renewNow($this->domain);
+        return LetsEncrypt::renewNow($this);
     }
 }
diff --git a/tests/Encoders/PemEncoderTest.php b/tests/Encoders/PemEncoderTest.php
new file mode 100644
index 0000000..9a9fc6d
--- /dev/null
+++ b/tests/Encoders/PemEncoderTest.php
@@ -0,0 +1,16 @@
+<?php
+
+namespace Daanra\LaravelLetsEncrypt\Tests\Encoders;
+
+use Daanra\LaravelLetsEncrypt\Encoders\PemEncoder;
+use Daanra\LaravelLetsEncrypt\Tests\TestCase;
+
+class PemEncoderTest extends TestCase
+{
+    /** @test */
+    public function test_encoder()
+    {
+        $this->assertEquals("test    test\n", PemEncoder::encode('  test    test  '));
+        $this->assertEquals("2test1\n", PemEncoder::encode('2test1'));
+    }
+}
diff --git a/tests/Models/LetsEncryptCertificateTest.php b/tests/Models/LetsEncryptCertificateTest.php
new file mode 100644
index 0000000..69198e7
--- /dev/null
+++ b/tests/Models/LetsEncryptCertificateTest.php
@@ -0,0 +1,102 @@
+<?php
+
+namespace Daanra\LaravelLetsEncrypt\Tests\Models;
+
+use Daanra\LaravelLetsEncrypt\Builders\LetsEncryptCertificateBuilder;
+use Daanra\LaravelLetsEncrypt\Collections\LetsEncryptCertificateCollection;
+use Daanra\LaravelLetsEncrypt\Facades\LetsEncrypt;
+use Daanra\LaravelLetsEncrypt\Jobs\RegisterAccount;
+use Daanra\LaravelLetsEncrypt\Jobs\RequestAuthorization;
+use Daanra\LaravelLetsEncrypt\Jobs\RequestCertificate;
+use Daanra\LaravelLetsEncrypt\Models\LetsEncryptCertificate;
+use Daanra\LaravelLetsEncrypt\Tests\TestCase;
+use Illuminate\Foundation\Bus\PendingDispatch;
+use Illuminate\Support\Facades\Queue;
+
+class LetsEncryptCertificateTest extends TestCase
+{
+    /** @test */
+    public function test_correct_builder_instance()
+    {
+        $builder = LetsEncryptCertificate::query();
+
+        $this->assertInstanceOf(LetsEncryptCertificateBuilder::class, $builder);
+    }
+
+    /** @test */
+    public function test_correct_collection_instance()
+    {
+        $collection = LetsEncryptCertificate::all();
+
+        $this->assertInstanceOf(LetsEncryptCertificateCollection::class, $collection);
+    }
+
+    /** @test */
+    public function test_has_expired_attribute()
+    {
+        $certificate = LetsEncryptCertificate::create([
+            'domain' => 'test1.test',
+        ]);
+
+        $this->assertFalse(
+            $certificate->has_expired,
+            'Certificate has not been issued so it should not be marked as expired.'
+        );
+
+        $certificate->update([
+            'last_renewed_at' => now(),
+            'created' => true,
+        ]);
+
+        $this->assertFalse($certificate->has_expired, 'Certificate has just been issued so should not be considered as expired.');
+
+        $certificate->update([
+            'last_renewed_at' => now()->subMonths(4),
+        ]);
+
+        $this->assertTrue($certificate->has_expired, 'Certificate has been issued 4 months ago so should be marked as expired.');
+    }
+
+    /** @test */
+    public function test_renew()
+    {
+        $certificate = LetsEncryptCertificate::create([
+            'domain' => 'test2.test',
+        ]);
+
+        Queue::fake();
+
+        $pendingDispatch = $certificate->renew();
+
+        $this->assertInstanceOf(PendingDispatch::class, $pendingDispatch);
+
+        // Jobs are only pushed after the pending dispatch leaves memory.
+        $pendingDispatch->__destruct();
+
+        Queue::assertPushedWithChain(RegisterAccount::class, [
+            new RequestAuthorization($certificate),
+            new RequestCertificate($certificate),
+        ]);
+    }
+
+    /** @test */
+    public function test_renew_now()
+    {
+        $certificate = LetsEncryptCertificate::create([
+            'domain' => 'test3.test',
+        ]);
+
+        Queue::fake();
+
+        LetsEncrypt::shouldReceive('renewNow')
+            ->once()
+            ->with($certificate)
+            ->andReturn($certificate);
+
+        $instance = $certificate->renewNow();
+
+        Queue::assertNothingPushed();
+
+        $this->assertEquals($certificate, $instance);
+    }
+}