diff --git a/default.nix b/default.nix
index a87c5f434d..604f1b831e 100644
--- a/default.nix
+++ b/default.nix
@@ -45,8 +45,9 @@ stdenv.mkDerivation {
   ] ++ lib.optionals stdenv.isLinux [ qtwayland ];
 
   cmakeFlags = [
+    "-DQON_QT6_BUILD=ON"
     "-DUSE_SYSTEM_BOTAN=1"
-    "-DBUILD_WITH_SYSTEM_BOTAN=1"
+    "-DBUILD_WITH_SYSTEM_BOTAN=ON"
   ];
 
   postInstall = ''