diff --git a/src/axolotl/utils/trainer.py b/src/axolotl/utils/trainer.py
index dc995fda8e..3fd4a137f1 100644
--- a/src/axolotl/utils/trainer.py
+++ b/src/axolotl/utils/trainer.py
@@ -302,6 +302,8 @@ def calc_sample_packing_eff_est(estimates: List[float]):
 
 def setup_fsdp_envs(cfg):
     os.environ["ACCELERATE_USE_FSDP"] = "true"
+    if cfg.fsdp_config.fsdp_activation_checkpointing:
+        os.environ["FSDP_ACTIVATION_CHECKPOINTING"] = "true"
     if cfg.fsdp_config.fsdp_offload_params:
         os.environ["FSDP_OFFLOAD_PARAMS"] = "true"
     if cfg.fsdp_config.fsdp_sync_module_states: