diff --git a/src/Indexer.php b/src/Indexer.php
index e411054..a9e3335 100644
--- a/src/Indexer.php
+++ b/src/Indexer.php
@@ -221,7 +221,7 @@ class Indexer
                 yield timeout();
                 $this->client->window->logMessage(MessageType::LOG, "Parsing $uri");
                 try {
-                    $document = yield $this->documentLoader->load($uri);
+                    $document = yield $this->documentLoader->load($uri, $this->options->fileSizeLimit);
                     if (!isVendored($document, $this->composerJson)) {
                         $this->client->textDocument->publishDiagnostics($uri, $document->getDiagnostics());
                     }
diff --git a/src/Options.php b/src/Options.php
index 48ba540..81a0fa5 100644
--- a/src/Options.php
+++ b/src/Options.php
@@ -12,6 +12,13 @@ class Options
      */
     public $fileTypes = ['.php'];
 
+    /**
+     * Maximum file size to index
+     *
+     * @var int
+     */
+    public $fileSizeLimit = 150000;
+
     /**
      * Validate/Filter input and set options for file types
      *
@@ -20,13 +27,29 @@ class Options
     public function setFileTypes(array $fileTypes)
     {
         $fileTypes = filter_var_array($fileTypes, FILTER_SANITIZE_STRING);
-        $fileTypes =  filter_var($fileTypes, FILTER_CALLBACK, ['options' => [$this, 'filterFileTypes']]);
+        $fileTypes = filter_var($fileTypes, FILTER_CALLBACK, ['options' => [$this, 'filterFileTypes']]);
         $fileTypes = array_filter($fileTypes, 'strlen');
         $fileTypes = array_values($fileTypes);
 
         $this->fileTypes = !empty($fileTypes) ? $fileTypes : $this->fileTypes;
     }
 
+    /**
+     * Validate/Filter input and set option for file size limit
+     *
+     * @param string $fileSizeLimit Size in human readable format or -1 for unlimited
+     */
+    public function setFileSizeLimit(string $fileSizeLimit)
+    {
+        $fileSizeLimit = filter_var($fileSizeLimit, FILTER_SANITIZE_STRING);
+
+        if ($fileSizeLimit === '-1') {
+            $this->fileSizeLimit = PHP_INT_MAX;
+        } else {
+            $this->fileSizeLimit = $this->convertFileSize($fileSizeLimit);
+        }
+    }
+
     /**
      * Filter valid file type
      *
@@ -47,4 +70,20 @@ class Options
 
         return $fileType;
     }
+
+    /**
+     * Convert human readable file size to byte
+     *
+     * @param string $fileSize
+     * @return int
+     */
+    private function convertFileSize(string $fileSize)
+    {
+        preg_match('/(\d+)(\w)/', $fileSize, $match);
+        $sizes = 'KMG';
+        $size = (int) $match[1];
+        $factor = strpos($sizes, strtoupper($match[2])) + 1;
+
+        return $size * pow(1000, $factor);
+    }
 }
diff --git a/src/PhpDocumentLoader.php b/src/PhpDocumentLoader.php
index 57a7e9c..7bcb067 100644
--- a/src/PhpDocumentLoader.php
+++ b/src/PhpDocumentLoader.php
@@ -100,13 +100,12 @@ class PhpDocumentLoader
      * The document is NOT added to the list of open documents, but definitions are registered.
      *
      * @param string $uri
+     * @param int $limit
      * @return Promise <PhpDocument>
      */
-    public function load(string $uri): Promise
+    public function load(string $uri, int $limit): Promise
     {
-        return coroutine(function () use ($uri) {
-
-            $limit = 150000;
+        return coroutine(function () use ($uri, $limit) {
             $content = yield $this->contentRetriever->retrieve($uri);
             $size = strlen($content);
             if ($size > $limit) {