diff --git a/backend/domain/simple_submission_checks/constraints/extension_not_present_constraint.py b/backend/domain/simple_submission_checks/constraints/extension_not_present_constraint.py
index 864cb750..1a5ddcbb 100644
--- a/backend/domain/simple_submission_checks/constraints/extension_not_present_constraint.py
+++ b/backend/domain/simple_submission_checks/constraints/extension_not_present_constraint.py
@@ -11,22 +11,22 @@
 
 class ExtensionNotPresentConstraint(BaseModel):
     type: ConstraintType = ConstraintType.EXTENSION_NOT_PRESENT
-    extension: str
+    not_present_extension: str
 
     def validate_constraint(self, path: Path) -> ExtensionNotPresentConstraintResult:
         directory = os.listdir(path)
 
-        files_with_extension = [file for file in directory if file.endswith(self.extension)]
+        files_with_extension = [file for file in directory if file.endswith(self.not_present_extension)]
 
         if files_with_extension:
             return ExtensionNotPresentConstraintResult(
-                extension=self.extension,
+                extension=self.not_present_extension,
                 is_ok=False,
                 files_with_extension=files_with_extension,
             )
 
         return ExtensionNotPresentConstraintResult(
-            extension=self.extension,
+            extension=self.not_present_extension,
             is_ok=True,
             files_with_extension=files_with_extension,
         )
diff --git a/backend/tests/test_simple_submissions/test_everything_not_ok.py b/backend/tests/test_simple_submissions/test_everything_not_ok.py
index 1736b29a..14833f8c 100644
--- a/backend/tests/test_simple_submissions/test_everything_not_ok.py
+++ b/backend/tests/test_simple_submissions/test_everything_not_ok.py
@@ -50,7 +50,7 @@ class FaultyProjectConstraintValidationTest(unittest.TestCase):
     submission_constraint = SubmissionConstraint(
         root_constraint=ZipConstraint(
             zip_name="project.zip",
-            global_constraints=[ExtensionNotPresentConstraint(extension=".exe")],
+            global_constraints=[ExtensionNotPresentConstraint(not_present_extension=".exe")],
             sub_constraints=[
                 DirectoryConstraint(
                     directory_name="src",
@@ -72,7 +72,7 @@ class FaultyProjectConstraintValidationTest(unittest.TestCase):
                 FileConstraint(file_name="README.md"),
                 FileConstraint(file_name=".gitignore"),
                 NotPresentConstraint(file_or_directory_name="dist"),
-                ExtensionNotPresentConstraint(extension=".log"),
+                ExtensionNotPresentConstraint(not_present_extension=".log"),
             ],
         ),
     )
diff --git a/backend/tests/test_simple_submissions/test_everything_ok.py b/backend/tests/test_simple_submissions/test_everything_ok.py
index 25dd3b27..7fafdb96 100644
--- a/backend/tests/test_simple_submissions/test_everything_ok.py
+++ b/backend/tests/test_simple_submissions/test_everything_ok.py
@@ -45,7 +45,7 @@ class EverythingOkTest(unittest.TestCase):
     submission_constraint = SubmissionConstraint(
         root_constraint=ZipConstraint(
             zip_name="project.zip",
-            global_constraints=[ExtensionNotPresentConstraint(extension=".exe")],
+            global_constraints=[ExtensionNotPresentConstraint(not_present_extension=".exe")],
             sub_constraints=[
                 DirectoryConstraint(
                     directory_name="src",
@@ -71,8 +71,8 @@ class EverythingOkTest(unittest.TestCase):
                 FileConstraint(file_name="README.md"),
                 FileConstraint(file_name=".gitignore"),
                 NotPresentConstraint(file_or_directory_name="dist"),
-                ExtensionNotPresentConstraint(extension=".class"),
-                ExtensionNotPresentConstraint(extension=".log"),
+                ExtensionNotPresentConstraint(not_present_extension=".class"),
+                ExtensionNotPresentConstraint(not_present_extension=".log"),
             ],
         ),
     )
diff --git a/backend/tests/test_simple_submissions/test_extension_not_present_constraint.py b/backend/tests/test_simple_submissions/test_extension_not_present_constraint.py
index c53c4912..7417fa7e 100644
--- a/backend/tests/test_simple_submissions/test_extension_not_present_constraint.py
+++ b/backend/tests/test_simple_submissions/test_extension_not_present_constraint.py
@@ -44,12 +44,13 @@ class ExtensionNotPresentConstraintValidationTest(unittest.TestCase):
             zip_name="submission.zip",
             global_constraints=[],
             sub_constraints=[
-                ExtensionNotPresentConstraint(extension=".java"),  # .java is present, should fail
-                ExtensionNotPresentConstraint(extension=".c"),     # .c is present, should fail
-                ExtensionNotPresentConstraint(extension=".cpp"),   # .cpp is not present, should pass
+                ExtensionNotPresentConstraint(not_present_extension=".java"),  # .java is present, should fail
+                ExtensionNotPresentConstraint(not_present_extension=".c"),     # .c is present, should fail
+                ExtensionNotPresentConstraint(not_present_extension=".cpp"),   # .cpp is not present, should pass
                 DirectoryConstraint(  # Directory is present, should pass
                     directory_name="no_txt_in_this_folder",
-                    sub_constraints=[ExtensionNotPresentConstraint(extension=".txt")],  # .txt is present, should fail
+                    sub_constraints=[ExtensionNotPresentConstraint(not_present_extension=".txt")],  # .txt is
+                    # present, should fail
                 ),
             ],
         ),
diff --git a/backend/tests/test_simple_submissions/test_global_constraint.py b/backend/tests/test_simple_submissions/test_global_constraint.py
index e3a7388e..3e7ef346 100644
--- a/backend/tests/test_simple_submissions/test_global_constraint.py
+++ b/backend/tests/test_simple_submissions/test_global_constraint.py
@@ -35,9 +35,9 @@ class GlobalConstraintValidationTest(unittest.TestCase):
         root_constraint=ZipConstraint(
             zip_name="submission.zip",
             global_constraints=[
-                ExtensionNotPresentConstraint(extension=".java"),
-                ExtensionNotPresentConstraint(extension=".c"),
-                ExtensionNotPresentConstraint(extension=".cpp"),
+                ExtensionNotPresentConstraint(not_present_extension=".java"),
+                ExtensionNotPresentConstraint(not_present_extension=".c"),
+                ExtensionNotPresentConstraint(not_present_extension=".cpp"),
                 NotPresentConstraint(file_or_directory_name="dir4"),
             ],
             sub_constraints=[],
diff --git a/frontend/src/components/SimpleTests/SimpleTests.tsx b/frontend/src/components/SimpleTests/SimpleTests.tsx
index c9c95c86..fb4d4d14 100644
--- a/frontend/src/components/SimpleTests/SimpleTests.tsx
+++ b/frontend/src/components/SimpleTests/SimpleTests.tsx
@@ -105,7 +105,7 @@ function json_to_submission(json: any): Submission {
                 break; 
             }
             case 'EXTENSION_NOT_PRESENT': { 
-                constraint = new Constraint('EXTENSION_NOT_PRESENT', json['extension'], id, parent_id, depth);
+                constraint = new Constraint('EXTENSION_NOT_PRESENT', json['not_present_extension'], id, parent_id, depth);
                 break; 
             }
             case 'EXTENSION_ONLY_PRESENT': { 
@@ -147,7 +147,7 @@ function json_to_submission(json: any): Submission {
                     break; 
                 }
                 case 'EXTENSION_NOT_PRESENT': { 
-                    constraint = new Constraint('EXTENSION_NOT_PRESENT', json['extension'], id, undefined, 0);
+                    constraint = new Constraint('EXTENSION_NOT_PRESENT', json['not_present_extension'], id, undefined, 0);
                     break; 
                 } 
                 case 'EXTENSION_ONLY_PRESENT': { 
@@ -194,7 +194,7 @@ function submission_to_json(submission: Submission): object {
                 constraint_object['file_or_directory_name'] = constraint.value;
                 break;
             case 'EXTENSION_NOT_PRESENT':
-                constraint_object['extension'] = constraint.value;
+                constraint_object['not_present_extension'] = constraint.value;
                 break;
             case 'EXTENSION_ONLY_PRESENT':
                 constraint_object['extension'] = constraint.value;