diff --git a/src/PhpDocument.php b/src/PhpDocument.php
index 75badca..214f97b 100644
--- a/src/PhpDocument.php
+++ b/src/PhpDocument.php
@@ -19,6 +19,7 @@ use phpDocumentor\Reflection\DocBlockFactory;
 use function LanguageServer\Fqn\{getDefinedFqn, getVariableDefinition, getReferencedFqn};
 use Sabre\Event\Promise;
 use function Sabre\Event\coroutine;
+use Sabre\Uri;
 
 class PhpDocument
 {
@@ -208,7 +209,20 @@ class PhpDocument
             $this->stmts = $stmts;
         }
 
-        $this->client->textDocument->publishDiagnostics($this->uri, $diagnostics);
+        if (!$this->isVendored()) {
+            $this->client->textDocument->publishDiagnostics($this->uri, $diagnostics);
+        }
+    }
+
+    /**
+     * Returns true if the document is a dependency
+     *
+     * @return bool
+     */
+    public function isVendored(): bool
+    {
+        $path = Uri\parse($this->uri)['path'];
+        return strpos($path, '/vendor/') !== false;
     }
 
     /**
diff --git a/tests/PhpDocumentTest.php b/tests/PhpDocumentTest.php
index 5cdc8c8..057551e 100644
--- a/tests/PhpDocumentTest.php
+++ b/tests/PhpDocumentTest.php
@@ -37,4 +37,22 @@ class PhpDocumentTest extends TestCase
         $this->assertInstanceOf(Node\Name\FullyQualified::class, $node);
         $this->assertEquals('SomeClass', (string)$node);
     }
+
+    public function testIsVendored()
+    {
+        $document = $this->project->openDocument('file:///dir/vendor/x.php', "<?php\n$\$a = new SomeClass;");
+        $this->assertEquals(true, $document->isVendored());
+
+        $document = $this->project->openDocument('file:///c:/dir/vendor/x.php', "<?php\n$\$a = new SomeClass;");
+        $this->assertEquals(true, $document->isVendored());
+
+        $document = $this->project->openDocument('file:///vendor/x.php', "<?php\n$\$a = new SomeClass;");
+        $this->assertEquals(true, $document->isVendored());
+
+        $document = $this->project->openDocument('file:///dir/vendor.php', "<?php\n$\$a = new SomeClass;");
+        $this->assertEquals(false, $document->isVendored());
+
+        $document = $this->project->openDocument('file:///dir/x.php', "<?php\n$\$a = new SomeClass;");
+        $this->assertEquals(false, $document->isVendored());
+    }
 }