diff --git a/src/axolotl/utils/schemas/config.py b/src/axolotl/utils/schemas/config.py
index bc7ee7e72..02308695c 100644
--- a/src/axolotl/utils/schemas/config.py
+++ b/src/axolotl/utils/schemas/config.py
@@ -512,10 +512,17 @@ class AxolotlInputConfig(
     @model_validator(mode="before")
     @classmethod
     def hint_sample_packing_padding(cls, data):
-        if data.get("sample_packing") and not data.get("pad_to_sequence_len"):
-            LOG.warning(
-                "`pad_to_sequence_len: true` is recommended when using sample_packing"
-            )
+        if data.get("sample_packing"):
+            pad_to_sequence_len = data.get("pad_to_sequence_len")
+            if pad_to_sequence_len is False:
+                LOG.warning(
+                    "`pad_to_sequence_len: true` is recommended when using sample_packing"
+                )
+            elif pad_to_sequence_len is None:
+                LOG.info(
+                    "Setting `pad_to_sequence_len: true` to prevent memory leaks when sample_packing"
+                )
+                data["pad_to_sequence_len"] = True
         return data
 
     @model_validator(mode="before")
diff --git a/tests/patched/test_validation.py b/tests/patched/test_validation.py
index 3262a6981..683db61b2 100644
--- a/tests/patched/test_validation.py
+++ b/tests/patched/test_validation.py
@@ -648,7 +648,7 @@ class TestValidation(BaseValidation):
             DictDefault(
                 {
                     "sample_packing": True,
-                    "pad_to_sequence_len": None,
+                    "pad_to_sequence_len": False,
                     "flash_attention": True,
                 }
             )
@@ -662,6 +662,26 @@ class TestValidation(BaseValidation):
                 for record in self._caplog.records
             )
 
+    def test_packing_autoset(self, minimal_cfg):
+        cfg = (
+            DictDefault(
+                {
+                    "sample_packing": True,
+                    "pad_to_sequence_len": None,
+                    "flash_attention": True,
+                }
+            )
+            | minimal_cfg
+        )
+        with self._caplog.at_level(logging.INFO):
+            cfg = validate_config(cfg)
+            assert any(
+                "Setting `pad_to_sequence_len: true` to prevent memory leaks when sample_packing"
+                in record.message
+                for record in self._caplog.records
+            )
+            assert cfg.pad_to_sequence_len is True
+
     def test_merge_lora_no_bf16_fail(self, minimal_cfg):
         """
         This is assumed to be run on a CPU machine, so bf16 is not supported.