diff --git a/php/tests/EncodeDecodeTest.php b/php/tests/EncodeDecodeTest.php
index 6368a18..d471a5a 100644
--- a/php/tests/EncodeDecodeTest.php
+++ b/php/tests/EncodeDecodeTest.php
@@ -14,6 +14,7 @@
 use Foo\TestBytesValue;
 use Foo\TestAny;
 use Foo\TestEnum;
+use Foo\TestLargeFieldNumber;
 use Foo\TestMessage;
 use Foo\TestMessage\Sub;
 use Foo\TestPackedMessage;
@@ -529,6 +530,15 @@
         $this->assertSame("", $data);
     }
 
+    public function testLargeFieldNumber()
+    {
+        $m = new TestLargeFieldNumber(['large_field_number' => 5]);
+        $data = $m->serializeToString();
+        $m2 = new TestLargeFieldNumber();
+        $m2->mergeFromString($data);
+        $this->assertSame(5, $m2->getLargeFieldNumber());
+    }
+
     public function testDecodeInvalidInt32()
     {
         $this->expectException(Exception::class);