diff --git a/pkgs/flarum/default.nix b/pkgs/flarum/default.nix
index a0e849c1..c333ab53 100644
--- a/pkgs/flarum/default.nix
+++ b/pkgs/flarum/default.nix
@@ -12,7 +12,7 @@ buildComposerProject (finalAttrs: {
   };
 
   composerLock = ./composer.lock;
-  vendorHash = "";
+  vendorHash = "sha256-KXC0kVuBXTqLlddWGEisSDChWE74nRNdUr+fieFTG1M=";
 
   meta = {
     changelog = "https://github.com/phpro/grumphp/releases/tag/v${finalAttrs.version}";