diff --git a/pfdl_scheduler/parser/pfdl_tree_visitor.py b/pfdl_scheduler/parser/pfdl_tree_visitor.py
index de0b979..2c7f5ec 100644
--- a/pfdl_scheduler/parser/pfdl_tree_visitor.py
+++ b/pfdl_scheduler/parser/pfdl_tree_visitor.py
@@ -367,7 +367,7 @@ def visitExpression(self, ctx: PFDLParser.ExpressionContext) -> Dict:
         if length == 2:
             un_op = self.get_content(ctx.children[0])
             ele = self.get_content(ctx.children[1])
-            return dict(unop=un_op, value=ele)
+            return dict(unOp=un_op, value=ele)
 
         if length == 3:
             left = self.get_content(ctx.children[0])
diff --git a/tests/unit_test/test_pfdl_tree_visitor.py b/tests/unit_test/test_pfdl_tree_visitor.py
index 97cc0fd..935dc2d 100644
--- a/tests/unit_test/test_pfdl_tree_visitor.py
+++ b/tests/unit_test/test_pfdl_tree_visitor.py
@@ -489,7 +489,7 @@ def test_visitWhileLoop(self):
         service = Service()
         condition = Condition()
 
-        expression = {"unop": "!", "value": "True"}
+        expression = {"unOp": "!", "value": "True"}
         with patch.object(self.visitor, "visitExpression", return_value=expression) as mock:
             with patch.object(
                 self.visitor, "visitStatement", MagicMock(side_effect=[service, condition])
@@ -584,7 +584,7 @@ def test_visitCondition(self):
 
         passed_statements = [service, while_loop]
 
-        expression = {"unop": "!", "value": "True"}
+        expression = {"unOp": "!", "value": "True"}
 
         # without failed
         with patch.object(self.visitor, "visitExpression", return_value=expression) as mock:
@@ -834,9 +834,9 @@ def test_visitExpression(self):
         ):
             expression = self.visitor.visitExpression(expression_context)
             self.assertEqual(len(expression), 2)
-            self.assertTrue("unop" in expression)
+            self.assertTrue("unOp" in expression)
             self.assertTrue("value" in expression)
-            self.assertEqual(expression, {"unop": "!", "value": "value"})
+            self.assertEqual(expression, {"unOp": "!", "value": "value"})
 
         # case length = 3
         expression_context.children = [
diff --git a/tests/unit_test/test_semantic_error_checker.py b/tests/unit_test/test_semantic_error_checker.py
index b848e30..607d128 100644
--- a/tests/unit_test/test_semantic_error_checker.py
+++ b/tests/unit_test/test_semantic_error_checker.py
@@ -1714,10 +1714,10 @@ def test_check_expression(self):
         self.assertFalse(self.checker.check_expression(variable_list_2, None, task))
 
         self.assertTrue(
-            self.checker.check_expression({"unop": "!", "value": variable_list}, None, task)
+            self.checker.check_expression({"unOp": "!", "value": variable_list}, None, task)
         )
         self.assertTrue(
-            self.checker.check_expression({"unop": "!", "value": variable_list_3}, None, task)
+            self.checker.check_expression({"unOp": "!", "value": variable_list_3}, None, task)
         )
 
         expression = {
@@ -1726,7 +1726,7 @@ def test_check_expression(self):
             "right": {"left": 5, "binOp": "<", "right": variable_list},
         }
         self.assertTrue(
-            self.checker.check_expression({"unop": "!", "value": expression}, None, task)
+            self.checker.check_expression({"unOp": "!", "value": expression}, None, task)
         )
         expression = {
             "left": variable_list_3,
@@ -1734,7 +1734,7 @@ def test_check_expression(self):
             "right": {"left": "(", "binOp": "true", "right": ")"},
         }
         self.assertTrue(
-            self.checker.check_expression({"unop": "!", "value": expression}, None, task)
+            self.checker.check_expression({"unOp": "!", "value": expression}, None, task)
         )
         expression = {
             "left": variable_list_3,
@@ -1746,14 +1746,14 @@ def test_check_expression(self):
             },
         }
         self.assertTrue(
-            self.checker.check_expression({"unop": "!", "value": expression}, None, task)
+            self.checker.check_expression({"unOp": "!", "value": expression}, None, task)
         )
 
         self.assertFalse(
-            self.checker.check_expression({"unop": "!", "value": variable_list_2}, None, task)
+            self.checker.check_expression({"unOp": "!", "value": variable_list_2}, None, task)
         )
         self.check_if_print_error_is_called(
-            self.checker.check_expression, {"unop": "!", "value": variable_list_2}, None, task
+            self.checker.check_expression, {"unOp": "!", "value": variable_list_2}, None, task
         )
 
         expression = {
@@ -1762,10 +1762,10 @@ def test_check_expression(self):
             "right": {"left": 5, "binOp": "<", "right": variable_list},
         }
         self.assertFalse(
-            self.checker.check_expression({"unop": "!", "value": expression}, None, task)
+            self.checker.check_expression({"unOp": "!", "value": expression}, None, task)
         )
         self.check_if_print_error_is_called(
-            self.checker.check_expression, {"unop": "!", "value": expression}, None, task
+            self.checker.check_expression, {"unOp": "!", "value": expression}, None, task
         )
 
         expression = {
@@ -1774,10 +1774,10 @@ def test_check_expression(self):
             "right": {"left": "True", "binOp": "<", "right": variable_list},
         }
         self.assertFalse(
-            self.checker.check_expression({"unop": "!", "value": expression}, None, task)
+            self.checker.check_expression({"unOp": "!", "value": expression}, None, task)
         )
         self.check_if_print_error_is_called(
-            self.checker.check_expression, {"unop": "!", "value": expression}, None, task
+            self.checker.check_expression, {"unOp": "!", "value": expression}, None, task
         )
 
         expression = {
@@ -1790,10 +1790,10 @@ def test_check_expression(self):
             },
         }
         self.assertFalse(
-            self.checker.check_expression({"unop": "!", "value": expression}, None, task)
+            self.checker.check_expression({"unOp": "!", "value": expression}, None, task)
         )
         self.check_if_print_error_is_called(
-            self.checker.check_expression, {"unop": "!", "value": expression}, None, task
+            self.checker.check_expression, {"unOp": "!", "value": expression}, None, task
         )
 
         self.assertTrue(
@@ -1990,10 +1990,10 @@ def test_check_unary_operation(self):
         variable_list_3 = ["variable", "attribute_3"]
 
         self.assertTrue(
-            self.checker.check_unary_operation({"unop": "!", "value": variable_list}, None, task)
+            self.checker.check_unary_operation({"unOp": "!", "value": variable_list}, None, task)
         )
         self.assertTrue(
-            self.checker.check_unary_operation({"unop": "!", "value": variable_list_3}, None, task)
+            self.checker.check_unary_operation({"unOp": "!", "value": variable_list_3}, None, task)
         )
 
         expression = {
@@ -2002,7 +2002,7 @@ def test_check_unary_operation(self):
             "right": {"left": 5, "binOp": "<", "right": variable_list},
         }
         self.assertTrue(
-            self.checker.check_unary_operation({"unop": "!", "value": expression}, None, task)
+            self.checker.check_unary_operation({"unOp": "!", "value": expression}, None, task)
         )
         expression = {
             "left": variable_list_3,
@@ -2010,7 +2010,7 @@ def test_check_unary_operation(self):
             "right": {"left": "(", "binOp": "true", "right": ")"},
         }
         self.assertTrue(
-            self.checker.check_unary_operation({"unop": "!", "value": expression}, None, task)
+            self.checker.check_unary_operation({"unOp": "!", "value": expression}, None, task)
         )
         expression = {
             "left": variable_list_3,
@@ -2022,11 +2022,11 @@ def test_check_unary_operation(self):
             },
         }
         self.assertTrue(
-            self.checker.check_unary_operation({"unop": "!", "value": expression}, None, task)
+            self.checker.check_unary_operation({"unOp": "!", "value": expression}, None, task)
         )
 
         self.assertFalse(
-            self.checker.check_unary_operation({"unop": "!", "value": variable_list_2}, None, task)
+            self.checker.check_unary_operation({"unOp": "!", "value": variable_list_2}, None, task)
         )
         expression = {
             "left": variable_list_2,
@@ -2034,7 +2034,7 @@ def test_check_unary_operation(self):
             "right": {"left": 5, "binOp": "<", "right": variable_list},
         }
         self.assertFalse(
-            self.checker.check_unary_operation({"unop": "!", "value": expression}, None, task)
+            self.checker.check_unary_operation({"unOp": "!", "value": expression}, None, task)
         )
         expression = {
             "left": variable_list_3,
@@ -2042,7 +2042,7 @@ def test_check_unary_operation(self):
             "right": {"left": "True", "binOp": "<", "right": variable_list},
         }
         self.assertFalse(
-            self.checker.check_unary_operation({"unop": "!", "value": expression}, None, task)
+            self.checker.check_unary_operation({"unOp": "!", "value": expression}, None, task)
         )
         expression = {
             "left": variable_list_3,
@@ -2054,7 +2054,7 @@ def test_check_unary_operation(self):
             },
         }
         self.assertFalse(
-            self.checker.check_unary_operation({"unop": "!", "value": expression}, None, task)
+            self.checker.check_unary_operation({"unOp": "!", "value": expression}, None, task)
         )
 
     def test_check_binary_operation(self):