diff --git a/mamba_ssm/__init__.py b/mamba_ssm/__init__.py
index f536fc98..b33e2dd8 100644
--- a/mamba_ssm/__init__.py
+++ b/mamba_ssm/__init__.py
@@ -3,3 +3,4 @@
 from mamba_ssm.ops.selective_scan_interface import selective_scan_fn, mamba_inner_fn
 from mamba_ssm.modules.mamba_simple import Mamba
 from mamba_ssm.models.mixer_seq_simple import MambaLMHeadModel
+from mamba_ssm.models.config_mamba import MambaConfig
diff --git a/mamba_ssm/models/config_mamba.py b/mamba_ssm/models/config_mamba.py
index ffd31abc..57ada96d 100644
--- a/mamba_ssm/models/config_mamba.py
+++ b/mamba_ssm/models/config_mamba.py
@@ -1,4 +1,5 @@
-from dataclasses import dataclass, field
+from dataclasses import dataclass, field, asdict
+import json
 
 
 @dataclass
@@ -12,3 +13,9 @@ class MambaConfig:
     residual_in_fp32: bool = True
     fused_add_norm: bool = True
     pad_vocab_size_multiple: int = 8
+
+    def to_json_string(self):
+        return json.dumps(asdict(self))
+
+    def to_dict(self):
+        return asdict(self)
diff --git a/mamba_ssm/models/mixer_seq_simple.py b/mamba_ssm/models/mixer_seq_simple.py
index 5b3ddfcf..132537ca 100644
--- a/mamba_ssm/models/mixer_seq_simple.py
+++ b/mamba_ssm/models/mixer_seq_simple.py
@@ -4,11 +4,13 @@
 from functools import partial
 import json
 import os
+from typing import Optional
 
 from collections import namedtuple
 
 import torch
 import torch.nn as nn
+from torch.nn import CrossEntropyLoss
 
 from mamba_ssm.models.config_mamba import MambaConfig
 from mamba_ssm.modules.mamba_simple import Mamba, Block
@@ -225,7 +227,12 @@ def tie_weights(self):
     def allocate_inference_cache(self, batch_size, max_seqlen, dtype=None, **kwargs):
         return self.backbone.allocate_inference_cache(batch_size, max_seqlen, dtype=dtype, **kwargs)
 
-    def forward(self, input_ids, position_ids=None, inference_params=None, num_last_tokens=0):
+    def forward(self,
+                input_ids: torch.LongTensor = None,
+                labels: Optional[torch.LongTensor] = None,
+                position_ids=None,
+                inference_params=None,
+                num_last_tokens=0):
         """
         "position_ids" is just to be compatible with Transformer generation. We don't use it.
         num_last_tokens: if > 0, only return the logits for the last n tokens
@@ -234,13 +241,29 @@ def forward(self, input_ids, position_ids=None, inference_params=None, num_last_
         if num_last_tokens > 0:
             hidden_states = hidden_states[:, -num_last_tokens:]
         lm_logits = self.lm_head(hidden_states)
-        CausalLMOutput = namedtuple("CausalLMOutput", ["logits"])
-        return CausalLMOutput(logits=lm_logits)
+
+        loss = None
+        if labels is not None:
+            # Shift so that tokens < n predict n
+            shift_logits = lm_logits[..., :-1, :].contiguous()
+            shift_labels = labels[..., 1:].contiguous()
+            # Flatten the tokens
+            loss_fct = CrossEntropyLoss()
+            shift_logits = shift_logits.view(-1, self.config.vocab_size)
+            shift_labels = shift_labels.view(-1)
+            # Enable model parallelism
+            shift_labels = shift_labels.to(shift_logits.device)
+            loss = loss_fct(shift_logits, shift_labels)
+
+            return {"loss": loss, "logits": lm_logits, "hidden_states": hidden_states,}
+        else:
+            CausalLMOutput = namedtuple("CausalLMOutput", ["logits", "hidden_states"])
+            return CausalLMOutput(logits=lm_logits, hidden_states=hidden_states,)
 
     @classmethod
     def from_pretrained(cls, pretrained_model_name, device=None, dtype=None, **kwargs):
         config_data = load_config_hf(pretrained_model_name)
-        config = MambaConfig(**config_data)
+        config = MambaConfig(**{k:v for k, v in config_data.items() if k not in ('_name_or_path', 'architectures',)})
         model = cls(config, device=device, dtype=dtype, **kwargs)
         model.load_state_dict(load_state_dict_hf(pretrained_model_name, device=device, dtype=dtype))
         return model