diff --git a/satpy/etc/readers/fci_l2_nc.yaml b/satpy/etc/readers/fci_l2_nc.yaml
index 3012a68ca1..819f32ead0 100644
--- a/satpy/etc/readers/fci_l2_nc.yaml
+++ b/satpy/etc/readers/fci_l2_nc.yaml
@@ -48,7 +48,6 @@ datasets:
     file_type: nc_fci_clm
     file_key: cloud_state
     long_name: cloud_mask_classification
-    fill_value: 0
 
   quality_illumination_clm:
     name: quality_illumination_clm
@@ -56,7 +55,6 @@ datasets:
     file_type: nc_fci_clm
     file_key: quality_illumination
     long_name: illumination_classification
-    fill_value: 0
 
   quality_nwp_parameters_clm:
     name: quality_nwp_parameters_clm
@@ -64,7 +62,6 @@ datasets:
     file_type: nc_fci_clm
     file_key: quality_nwp_parameters
     long_name: quality_index
-    fill_value: 0
 
   quality_MTG_parameters_clm:
     name: quality_MTG_parameters_clm
@@ -72,7 +69,7 @@ datasets:
     file_type: nc_fci_clm
     file_key: quality_MTG_parameters
     long_name: quality_index
-    fill_value: [-127, 0]
+    fill_value: -127
 
   quality_overall_processing_clm:
     name: quality_overall_processing_clm
@@ -80,7 +77,6 @@ datasets:
     file_type: nc_fci_clm
     file_key: quality_overall_processing
     long_name: quality_index
-    fill_value: 0
 
   product_quality_clm:
     name: product_quality_clm
@@ -107,7 +103,6 @@ datasets:
     file_type: nc_fci_ct
     file_key: cloud_phase
     long_name: cloud_phase
-    fill_value: 0
 
   cloud_type:
     name: cloud_type
@@ -115,7 +110,6 @@ datasets:
     file_type: nc_fci_ct
     file_key: cloud_type
     long_name: cloud_type
-    fill_value: 0
 
   quality_illumination_ct:
     name: quality_illumination_ct
@@ -123,7 +117,6 @@ datasets:
     file_type: nc_fci_ct
     file_key: quality_illumination
     long_name: illumination_classification
-    fill_value: 0
 
   quality_nwp_parameters_ct:
     name: quality_nwp_parameters_ct
@@ -131,7 +124,6 @@ datasets:
     file_type: nc_fci_ct
     file_key: quality_nwp_parameters
     long_name: quality_index
-    fill_value: 0
 
   quality_MTG_parameters_ct:
     name: quality_MTG_parameters_ct
@@ -139,7 +131,6 @@ datasets:
     file_type: nc_fci_ct
     file_key: quality_MTG_parameters
     long_name: quality_index
-    fill_value: 0
 
   quality_overall_processing_ct:
     name: quality_overall_processing_ct
@@ -147,7 +138,6 @@ datasets:
     file_type: nc_fci_ct
     file_key: quality_overall_processing
     long_name: quality_index
-    fill_value: 0
 
   product_quality_ct:
     name: product_quality_ct
@@ -173,7 +163,6 @@ datasets:
     resolution: 2000
     file_type: nc_fci_ctth
     file_key: cloud_top_aviation_height
-    fill_value: 0
 
   cloud_top_height:
     name: cloud_top_height
@@ -207,7 +196,6 @@ datasets:
     resolution: 2000
     file_type: nc_fci_ctth
     file_key: quality_status
-    fill_value: 0
 
   quality_rtm_ctth:
     name: quality_rtm_ctth
@@ -220,35 +208,31 @@ datasets:
     resolution: 2000
     file_type: nc_fci_ctth
     file_key: quality_method
-    fill_value: 0
 
   quality_nwp_parameters_ctth:
     name: quality_nwp_parameters_ctth
     resolution: 2000
     file_type: nc_fci_ctth
     file_key: quality_nwp_parameters
-    fill_value: 0
 
   quality_MTG_parameters_ctth:
     name: quality_MTG_parameters_ctth
     resolution: 2000
     file_type: nc_fci_ctth
     file_key: quality_MTG_parameters
-    fill_value: [-127, 0]
+    fill_value: -127
 
   quality_overall_processing_ctth:
     name: quality_overall_processing_ctth
     resolution: 2000
     file_type: nc_fci_ctth
     file_key: quality_overall_processing
-    fill_value: 0
 
   quality_overall_processing_aviation_ctth:
     name: quality_overall_processing_aviation_ctth
     resolution: 2000
     file_type: nc_fci_ctth
     file_key: quality_overall_processing_aviation
-    fill_value: 0
 
   product_quality_ctth:
     name: product_quality_ctth
@@ -275,7 +259,6 @@ datasets:
     file_type: nc_fci_oca
     file_key: retrieved_cloud_phase
     standard_name: thermodynamic_phase_of_cloud_water_particles_at_cloud_top
-    fill_value: 0
 
   retrieved_cloud_optical_thickness:
     name: retrieved_cloud_optical_thickness
diff --git a/satpy/readers/fci_l2_nc.py b/satpy/readers/fci_l2_nc.py
index 1a2a22dabe..b3ea79c81a 100644
--- a/satpy/readers/fci_l2_nc.py
+++ b/satpy/readers/fci_l2_nc.py
@@ -240,9 +240,12 @@ def _get_proj_area(self, dataset_id):
         """Extract projection and area information."""
         # Read the projection data from the mtg_geos_projection variable
         a = float(self._projection.attrs['semi_major_axis'])
-        rf = float(self._projection.attrs['inverse_flattering'])
         h = float(self._projection.attrs['perspective_point_height'])
 
+        # Some L2PF test data files have a typo in the keyname for the inverse flattening parameter. Use a default value
+        # as fallback until all L2PF test files are correctly formatted.
+        rf = float(self._projection.attrs.get('inverse_flattening', 298.257223563))
+
         res = dataset_id.resolution
 
         area_naming_input_dict = {'platform_name': 'mtg',
diff --git a/satpy/tests/reader_tests/test_fci_l2_nc.py b/satpy/tests/reader_tests/test_fci_l2_nc.py
index 2c5b30a643..9ebbdb32e7 100644
--- a/satpy/tests/reader_tests/test_fci_l2_nc.py
+++ b/satpy/tests/reader_tests/test_fci_l2_nc.py
@@ -99,7 +99,7 @@ def setUp(self):
             mtg_geos_projection = nc.createVariable('mtg_geos_projection', int, dimensions=())
             mtg_geos_projection.longitude_of_projection_origin = 0.0
             mtg_geos_projection.semi_major_axis = 6378137.
-            mtg_geos_projection.inverse_flattering = 298.257223563
+            mtg_geos_projection.inverse_flattening = 298.257223563
             mtg_geos_projection.perspective_point_height = 35786400.
 
         self.fh = FciL2NCFileHandler(filename=self.test_file, filename_info={}, filetype_info={})
@@ -461,7 +461,7 @@ def setUp(self):
             mtg_geos_projection = nc_byte.createVariable('mtg_geos_projection', int, dimensions=())
             mtg_geos_projection.longitude_of_projection_origin = 0.0
             mtg_geos_projection.semi_major_axis = 6378137.
-            mtg_geos_projection.inverse_flattering = 298.257223563
+            mtg_geos_projection.inverse_flattening = 298.257223563
             mtg_geos_projection.perspective_point_height = 35786400.
 
             test_dataset = nc_byte.createVariable('cloud_mask_test_flag', np.float32,