diff --git a/level1c4pps/__init__.py b/level1c4pps/__init__.py
index 6299c08..5c9de31 100644
--- a/level1c4pps/__init__.py
+++ b/level1c4pps/__init__.py
@@ -488,7 +488,11 @@ def update_angle_attributes(scene, band):
 
 
 def apply_sunz_correction(scene, REFL_BANDS):
-    """Apply sun zenith angle correciton to visual channels."""
+    """Apply sun zenith angle correciton to visual channels.
+
+    Reference https://journals.ametsoc.org/view/journals/atsc/63/4/jas3682.1.xml
+
+    """
     sza = scene['sunzenith']
     mu0 = np.cos(np.radians(sza))
     scaler = 24.35 / (2 * mu0 + np.sqrt(498.5225 * mu0 * mu0 + 1))
diff --git a/level1c4pps/metimage2pps_lib.py b/level1c4pps/metimage2pps_lib.py
index c45abb4..c1de6b9 100644
--- a/level1c4pps/metimage2pps_lib.py
+++ b/level1c4pps/metimage2pps_lib.py
@@ -186,3 +186,4 @@ def process_one_scene(scene_files, out_path,
     print("Saved file {:s} after {:3.1f} seconds".format(
         os.path.basename(filename),
         time.time()-tic))
+    return filename