diff --git a/calculate/templates/template_engine.py b/calculate/templates/template_engine.py
index fd75a33..cddd647 100644
--- a/calculate/templates/template_engine.py
+++ b/calculate/templates/template_engine.py
@@ -984,6 +984,7 @@ class CalculateExtension(Extension):
 
         self.tags = {'calculate', 'save', 'set_var'}
         self.CONDITION_TOKENS_TYPES = {'eq', 'ne', 'lt', 'gt', 'lteq', 'gteq'}
+        self.CONDITION_NAME_TOKENS = {'not'}
         self.LITERAL_TOKENS_TYPES = {'string', 'integer', 'float'}
 
         if hasattr(self._datavars, 'variables_to_save'):
@@ -1069,7 +1070,9 @@ class CalculateExtension(Extension):
                 and self.stream.current.value in self._parameters_set
                     and self.stream.look().type != 'dot'
                     and self.stream.look().type not in
-                    self.CONDITION_TOKENS_TYPES):
+                    self.CONDITION_TOKENS_TYPES
+                    and self.stream.current.value not in
+                    self.CONDITION_NAME_TOKENS):
                 # разбираем параметр.
                 # pairs_list.append(self.get_parameter_node())
                 name_node, value_node = self._get_parameter()
@@ -1091,7 +1094,8 @@ class CalculateExtension(Extension):
 
             elif (self._is_variable_name(self.stream.current)
                   or self.stream.current.type == 'lparen'
-                  or self.stream.current.type == 'integer'):
+                  or self.stream.current.type == 'integer'
+                  or self.stream.current.value in self.CONDITION_NAME_TOKENS):
                 # разбираем условие. Если условие False -- кидаем исключение.
                 # condition_result = self.get_condition_result()
                 # if not condition_result:
diff --git a/tests/templates/test_template_engine.py b/tests/templates/test_template_engine.py
index 436bb8a..2964cb6 100644
--- a/tests/templates/test_template_engine.py
+++ b/tests/templates/test_template_engine.py
@@ -66,7 +66,7 @@ class TestTemplateEngine():
                 output_parameters.env == {datavars_module['other_vars']})
 
     def test_if_an_input_template_contains_condition_and_it_is_True__the_template_engine_object_will_be_initialized_without_any_exceptions(self):
-        input_template = '''{% calculate vars.var_1 < vars.var_2 or (not (var_3 == 'required status') and vars.var_4), env = 'vars' %}'''
+        input_template = '''{% calculate not (var_3 == 'required status') and vars.var_4 or vars.var_1 < vars.var_2, env = 'vars' %}'''
         datavars_module = Variables({'vars':
                                      Variables({'var_1': 12,
                                                 'var_2': 1.2,