diff --git a/src/CSET/operators/read.py b/src/CSET/operators/read.py
index 41b7949c2..c75338037 100644
--- a/src/CSET/operators/read.py
+++ b/src/CSET/operators/read.py
@@ -304,6 +304,7 @@ def _check_input_files(input_path: Path | str, filename_pattern: str) -> Iterabl
     FileNotFoundError:
         If the provided arguments don't resolve to at least one existing file.
     """
+    logging.debug("Checking '%s' for pattern '%s'", input_path, filename_pattern)
     # Convert string paths into Path objects.
     if isinstance(input_path, str):
         input_path = Path(input_path)
diff --git a/src/CSET/recipes/generic_plevel_histogram_series.yaml b/src/CSET/recipes/generic_plevel_histogram_series.yaml
index bca484607..13133953a 100644
--- a/src/CSET/recipes/generic_plevel_histogram_series.yaml
+++ b/src/CSET/recipes/generic_plevel_histogram_series.yaml
@@ -18,7 +18,7 @@ steps:
         varname: $VARNAME
       model_level_constraint:
         operator: constraints.generate_level_constraint
-        coordinate: "model_level_number"
+        coordinate: pressure
         levels: $PLEVEL
 
   - operator: plot.plot_histogram_series