diff --git a/src/tlo/methods/malaria.py b/src/tlo/methods/malaria.py
index f58264613b..d90fe76340 100644
--- a/src/tlo/methods/malaria.py
+++ b/src/tlo/methods/malaria.py
@@ -226,7 +226,7 @@ def __init__(self, name=None):
         'ma_iptp': Property(Types.BOOL, 'if woman has IPTp in current pregnancy'),
     }
 
-    def read_parameters(self, resourcefilepath=None):
+    def read_parameters(self, resourcefilepath: Optional[Path] = None):
         # workbook = pd.read_excel(resourcefilepath / 'malaria' / 'ResourceFile_malaria.xlsx', sheet_name=None)
         workbook = read_csv_files(Path(resourcefilepath) / 'malaria' / 'ResourceFile_malaria', files=None)
         self.load_parameters_from_dataframe(workbook['parameters'])
@@ -241,9 +241,9 @@ def read_parameters(self, resourcefilepath=None):
         p['rdt_testing_rates'] = workbook['WHO_TestData2023']
         p['highrisk_districts'] = workbook['highrisk_districts']
 
-        inf_inc_sheet = pd.read_csv(Path(resourcefilepath) / 'malaria' / 'ResourceFile_malaria_InfInc_expanded.csv')
-        clin_inc_sheet = pd.read_csv(Path(resourcefilepath) / 'malaria' / 'ResourceFile_malaria_ClinInc_expanded.csv')
-        sev_inc_sheet = pd.read_csv(Path(resourcefilepath) / 'malaria' / 'ResourceFile_malaria_SevInc_expanded.csv')
+        inf_inc_sheet = pd.read_csv(resourcefilepath / 'malaria' / 'ResourceFile_malaria_InfInc_expanded.csv')
+        clin_inc_sheet = pd.read_csv(resourcefilepath / 'malaria' / 'ResourceFile_malaria_ClinInc_expanded.csv')
+        sev_inc_sheet = pd.read_csv(resourcefilepath / 'malaria' / 'ResourceFile_malaria_SevInc_expanded.csv')
 
         # load parameters for scale-up projections
         p['scaleup_parameters'] = workbook["scaleup_parameters"]