diff --git a/stand/api.py b/stand/api.py
index cfb2c35..afd00ea 100644
--- a/stand/api.py
+++ b/stand/api.py
@@ -13,19 +13,19 @@ router = APIRouter()
 
 @router.post("/tables/{pgroup}/append")
 def append(beamline: Beamline, pgroup: PGroup, run: int, row: dict[str, Any]):
-    timestamp = row.pop("timestamp", None)
-    timestamp = datetime.fromisoformat(timestamp) if timestamp else datetime.now()
-    row = {"timestamp": timestamp, **row} # setdefault would not force timestamp to be the first column
+    lib = adb.get(beamline)
 
     index = pd.Timestamp(run) # adb supports update only for timeseries indexes
     index = pd.Index([index], name="run")
 
-    lib = adb.get(beamline)
-
     run_exists = not lib.read(pgroup, date_range=index, columns=[]).data.index.empty
     if run_exists:
         raise HTTPException(409, f"run {run} exists already in {beamline}/{pgroup}")
 
+    timestamp = row.pop("timestamp", None)
+    timestamp = datetime.fromisoformat(timestamp) if timestamp else datetime.now()
+    row = {"timestamp": timestamp, **row} # setdefault would not force timestamp to be the first column
+
     df = pd.DataFrame(row, index=index)
     lib.append(pgroup, df)