diff --git a/flux_train.py b/flux_train.py
index 9bb58c0f..5228ec13 100644
--- a/flux_train.py
+++ b/flux_train.py
@@ -384,7 +384,7 @@ def train(args):
         optimizer_train_fn = lambda: None  # dummy function
         optimizer_eval_fn = lambda: None  # dummy function
 
-        if (args.optimizer_type not in fused_optimizers_supported) and args.full_bf16:
+        if (args.optimizer_type in fused_optimizers_supported) and args.full_bf16:
             logger.warning("Use of --blockwise_fused_optimizers is preventing stochastic/Kahan weight updates.")
     else:
         _, _, optimizer = train_util.get_optimizer(args, trainable_params=params_to_optimize)