diff --git a/atlas/models.py b/atlas/models.py
index fffb6f9b..89d20ca0 100644
--- a/atlas/models.py
+++ b/atlas/models.py
@@ -946,7 +946,7 @@ class UncategorisedDicom(models.Model):
 
     def get_basic_dicom_tags(self, dataset=None):
         try:
-            if dataset = is None:
+            if dataset is None:
                 dataset =  pydicom.read_file(self.image)
             to_include = (
                 "StudyDescription",