diff --git a/src/LanguageServer.php b/src/LanguageServer.php
index a30992bc..38dfeb1e 100644
--- a/src/LanguageServer.php
+++ b/src/LanguageServer.php
@@ -167,7 +167,7 @@ public function __construct(ProtocolReader $reader, ProtocolWriter $writer)
      */
     public function initialize(ClientCapabilities $capabilities, string $rootPath = null, int $processId = null, string $rootUri = null): Promise
     {
-        if ($rootPath === null) {
+        if ($rootPath === null && $rootUri !== null) {
             $rootPath = uriToPath($rootUri);
         }
         return coroutine(function () use ($capabilities, $rootPath, $processId) {