diff --git a/CAL/CalibrationProcessing/lib/processing/averaging.py b/CAL/CalibrationProcessing/lib/processing/averaging.py
index c761ec8b9dfc0dd090541c5cbbc9b26c312ce491..3fcf85ca719011f4e446a2fdbd2e9a440b3fb09c 100644
--- a/CAL/CalibrationProcessing/lib/processing/averaging.py
+++ b/CAL/CalibrationProcessing/lib/processing/averaging.py
@@ -262,7 +262,7 @@ def average_dataset_by_sample(input_data_set, window_size):
     if input_data_set is not None:
         if isinstance(input_data_set, HolographyDataset) is True:
             dataset = input_data_set
-        elif isinstance(str, input_data_set):
+        elif isinstance(input_data_set, str):
             dataset = HolographyDataset.load_from_file(input_data_set)
         else:
             text = "Cannot average data by samples!  The input data is neither an HDS not a string."
@@ -274,7 +274,7 @@ def average_dataset_by_sample(input_data_set, window_size):
         logger.error(text)
         raise ValueError(text)
 
-    if isinstance(int, window_size) is False or window_size < 1:
+    if isinstance(window_size, int) is False or window_size < 1:
         text = "Cannot average data by samples!  The window size must be an integer value bigger than 0."
         logger.error(text)
         raise ValueError(text)