diff --git a/pkgs/by-name/ma/mailpit/package.nix b/pkgs/by-name/ma/mailpit/package.nix
index 4b0341c59ee2..fdc3d4831c2e 100644
--- a/pkgs/by-name/ma/mailpit/package.nix
+++ b/pkgs/by-name/ma/mailpit/package.nix
@@ -43,6 +43,9 @@ let
       hash = source.npmDepsHash;
     };
 
+    # error "C++20 or later required." for dependency node_modules/tree-sitter
+    env.NIX_CFLAGS_COMPILE = "-std=c++20";
+
     nativeBuildInputs = [
       nodejs
       python3