diff --git a/src/Notebook_Processor/notebook_models/notebook_cell_model.py b/src/Notebook_Processor/notebook_models/notebook_cell_model.py
index 24a8743d2bc03f8e63e02d7921461e7ff4101571..877656750146d451b40a4f40f08908a861ff6b2b 100644
--- a/src/Notebook_Processor/notebook_models/notebook_cell_model.py
+++ b/src/Notebook_Processor/notebook_models/notebook_cell_model.py
@@ -85,6 +85,7 @@ class NotebookMarkdownCellModel(BaseNotebookCellModel):
     "Notebook markdown cell."
     """
     cell_type: Literal["markdown"]
+    attachments: Optional[dict] = Field(default=None, description="Media attachments (e.g. inline images), stored as mimebundle keyed by filename.")
 
 
 class NotebookCodeCellModel(BaseNotebookCellModel):