diff --git a/RAT/inputs.py b/RAT/inputs.py
index a305a1a0..a44d5816 100644
--- a/RAT/inputs.py
+++ b/RAT/inputs.py
@@ -207,21 +207,6 @@ def make_cells(project: RAT.Project) -> Cells:
             data_limits.append([0.0, 0.0])
             simulation_limits.append([0.0, 0.0])
 
-    # Set wrappers for custom function files
-    file_list = []
-    for custom_file in project.custom_files:
-
-        if custom_file.language == Languages.Matlab:
-            wrapper = RAT.wrappers.MatlabWrapper(custom_file.filename)
-            file = wrapper.getHandle()
-        elif custom_file.language == Languages.Cpp:
-            wrapper = RAT.wrappers.DylibWrapper(custom_file.filename, pathlib.PurePath(custom_file.filename).stem)
-            file = wrapper.getHandle()
-        else:
-            file = custom_file.filename
-
-        file_list.append(pathlib.PurePath(file).stem)
-
     # Populate the set of cells
     cells = Cells()
     cells.f1 = [[0, 1]] * len(project.contrasts)  # This is marked as "to do" in RAT
@@ -237,7 +222,7 @@ def make_cells(project: RAT.Project) -> Cells:
     cells.f11 = [param.name for param in project.bulk_in]
     cells.f12 = [param.name for param in project.bulk_out]
     cells.f13 = [param.name for param in project.resolution_parameters]
-    cells.f14 = file_list
+    cells.f14 = [pathlib.Path(file.filename).stem for file in project.custom_files]
     cells.f15 = [param.type for param in project.backgrounds]
     cells.f16 = [param.type for param in project.resolutions]
 
diff --git a/tests/test_inputs.py b/tests/test_inputs.py
index 2b445fc4..8382ee79 100644
--- a/tests/test_inputs.py
+++ b/tests/test_inputs.py
@@ -16,7 +16,7 @@ def standard_layers_project():
     """Add parameters to the default project for a non polarised calculation."""
     test_project = RAT.Project(data=RAT.ClassList([RAT.models.Data(name='Simulation', data=np.array([[1.0, 1.0, 1.0]]))]))
     test_project.parameters.append(name='Test SLD')
-    test_project.custom_files.append(name='Test Custom File')
+    test_project.custom_files.append(name='Test Custom File', filename='matlab_test.m', language='matlab')
     test_project.layers.append(name='Test Layer', SLD='Test SLD')
     test_project.contrasts.append(name='Test Contrast', data='Simulation', background='Background 1', bulk_in='SLD Air',
                                   bulk_out='SLD D2O', scalefactor='Scalefactor 1', resolution='Resolution 1',
@@ -30,7 +30,7 @@ def domains_project():
     test_project = RAT.Project(calculation=RAT.utils.enums.Calculations.Domains,
                                data=RAT.ClassList([RAT.models.Data(name='Simulation', data=np.array([[1.0, 1.0, 1.0]]))]))
     test_project.parameters.append(name='Test SLD')
-    test_project.custom_files.append(name='Test Custom File')
+    test_project.custom_files.append(name='Test Custom File', filename='matlab_test.m', language='matlab')
     test_project.layers.append(name='Test Layer', SLD='Test SLD')
     test_project.domain_contrasts.append(name='up', model=['Test Layer'])
     test_project.domain_contrasts.append(name='down', model=['Test Layer'])
@@ -45,7 +45,7 @@ def custom_xy_project():
     """Add parameters to the default project for a non polarised calculation and use the custom xy model."""
     test_project = RAT.Project(model=RAT.utils.enums.Models.CustomXY)
     test_project.parameters.append(name='Test SLD')
-    test_project.custom_files.append(name='Test Custom File')
+    test_project.custom_files.append(name='Test Custom File', filename='matlab_test.m', language='matlab')
     test_project.contrasts.append(name='Test Contrast', data='Simulation', background='Background 1', bulk_in='SLD Air',
                                   bulk_out='SLD D2O', scalefactor='Scalefactor 1', resolution='Resolution 1',
                                   model=['Test Custom File'])
@@ -189,7 +189,7 @@ def standard_layers_cells():
     cells.f11 = ['SLD Air']
     cells.f12 = ['SLD D2O']
     cells.f13 = ['Resolution Param 1']
-    cells.f14 = ['']
+    cells.f14 = ['matlab_test']
     cells.f15 = [RAT.models.Types.Constant]
     cells.f16 = [RAT.models.Types.Constant]
     cells.f17 = [[0.0, 0.0, 0.0]]
@@ -217,7 +217,7 @@ def domains_cells():
     cells.f11 = ['SLD Air']
     cells.f12 = ['SLD D2O']
     cells.f13 = ['Resolution Param 1']
-    cells.f14 = ['']
+    cells.f14 = ['matlab_test']
     cells.f15 = [RAT.models.Types.Constant]
     cells.f16 = [RAT.models.Types.Constant]
     cells.f17 = [[0.0, 0.0, 0.0]]
@@ -245,7 +245,7 @@ def custom_xy_cells():
     cells.f11 = ['SLD Air']
     cells.f12 = ['SLD D2O']
     cells.f13 = ['Resolution Param 1']
-    cells.f14 = ['']
+    cells.f14 = ['matlab_test']
     cells.f15 = [RAT.models.Types.Constant]
     cells.f16 = [RAT.models.Types.Constant]
     cells.f17 = [[0.0, 0.0, 0.0]]