diff --git a/assume/common/outputs.py b/assume/common/outputs.py
index 9d34b4efb..392644f86 100644
--- a/assume/common/outputs.py
+++ b/assume/common/outputs.py
@@ -318,8 +318,8 @@ def write_market_dispatch(self, data):
         :type data: any
         """
         df = pd.DataFrame(data, columns=["datetime", "power", "market_id", "unit_id"])
-        df["simulation"] = self.simulation_id
         if not df.empty:
+            df["simulation"] = self.simulation_id
             self.write_dfs["market_dispatch"].append(df)
 
     def write_unit_dispatch(self, data):
diff --git a/tests/test_outputs.py b/tests/test_outputs.py
index 34ac755af..4c8a3ba33 100644
--- a/tests/test_outputs.py
+++ b/tests/test_outputs.py
@@ -114,6 +114,15 @@ def test_output_market_dispatch():
     meta = {"sender_id": None}
     content = {"context": "write_results", "type": "market_dispatch", "data": []}
     output_writer.handle_message(content, meta)
+    # empty dfs are discarded
+    assert len(output_writer.write_dfs["market_dispatch"]) == 0, "market_dispatch"
+
+    content = {
+        "context": "write_results",
+        "type": "market_dispatch",
+        "data": [[start, 90, "EOM", "TestUnit"]],
+    }
+    output_writer.handle_message(content, meta)
     assert len(output_writer.write_dfs["market_dispatch"]) == 1, "market_dispatch"