diff --git a/pyproject.toml b/pyproject.toml
index c531d5e0..16a46670 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -96,7 +96,7 @@ docs = [
 ]
 all_extras = [
   "hyperactive[integrations]",
-  "optuna<5",
+  "optuna<6",
   "cmaes",  # Required for CmaEsOptimizer (optuna's CMA-ES sampler)
   "lightning",
   "lightgbm",