diff --git a/megatron/core/models/gpt/gpt_model.py b/megatron/core/models/gpt/gpt_model.py
index d2582a3f353..869a448eb2c 100644
--- a/megatron/core/models/gpt/gpt_model.py
+++ b/megatron/core/models/gpt/gpt_model.py
@@ -332,6 +332,14 @@ def _preprocess(
                     f"input_ids shape {input_ids.shape}"
                 )
             decoder_input = self.embedding(input_ids=input_ids, position_ids=position_ids)
+            if self.config.sequence_parallel and not self.embedding.scatter_to_sequence_parallel:
+                # Some models build the embedding to not scatter for sequence parallelism (e.g.
+                # VLM language models, whose outer multimodal model scatters the merged
+                # vision/audio+text embeddings itself). When such a model is run standalone
+                # (input_ids, no external decoder_input) -- e.g. language-model-only
+                # distillation/PTQ -- scatter here so the decoder sees a sequence-parallel
+                # sharded sequence and the output-side gather does not double the sequence.
+                decoder_input = tensor_parallel.scatter_to_sequence_parallel_region(decoder_input)
             if padding_mask is not None and self.config.sequence_parallel:
                 padding_mask = (
                     tensor_parallel.scatter_to_sequence_parallel_region(