diff --git a/vitrage/api_handler/apis/template.py b/vitrage/api_handler/apis/template.py
index 04301cc6c..76c291de9 100644
--- a/vitrage/api_handler/apis/template.py
+++ b/vitrage/api_handler/apis/template.py
@@ -34,7 +34,11 @@ class TemplateApis(object):
     FAILED_MSG = 'validation failed'
     OK_MSG = 'validation OK'
 
-    def __init__(self, templates, def_templates={}):
+    def __init__(self, templates, def_templates=None):
+
+        if def_templates is None:
+            def_templates = {}
+
         self.def_templates = def_templates
         self.templates = templates
 
diff --git a/vitrage/evaluator/template_data.py b/vitrage/evaluator/template_data.py
index f0210a1c9..046016ab7 100644
--- a/vitrage/evaluator/template_data.py
+++ b/vitrage/evaluator/template_data.py
@@ -78,7 +78,10 @@ class TemplateData(object):
         'operational_severity': VProps.VITRAGE_OPERATIONAL_SEVERITY
     }
 
-    def __init__(self, template_def, def_templates={}):
+    def __init__(self, template_def, def_templates=None):
+
+        if def_templates is None:
+            def_templates = {}
 
         self.name = template_def[TFields.METADATA][TFields.NAME]
         defs = {}
diff --git a/vitrage/evaluator/template_validation/content/template_content_validator.py b/vitrage/evaluator/template_validation/content/template_content_validator.py
index ef56d5adf..5600e507f 100644
--- a/vitrage/evaluator/template_validation/content/template_content_validator.py
+++ b/vitrage/evaluator/template_validation/content/template_content_validator.py
@@ -49,7 +49,10 @@ from vitrage.utils import evaluator as evaluator_utils
 LOG = log.getLogger(__name__)
 
 
-def content_validation(template, def_templates={}):
+def content_validation(template, def_templates=None):
+
+    if def_templates is None:
+        def_templates = {}
 
     result = get_content_correct_result()
     entities_index = {}
diff --git a/vitrage/tests/unit/evaluator/template_validation/content/test_template_content_validator.py b/vitrage/tests/unit/evaluator/template_validation/content/test_template_content_validator.py
index dca27a5f0..f07443f6c 100644
--- a/vitrage/tests/unit/evaluator/template_validation/content/test_template_content_validator.py
+++ b/vitrage/tests/unit/evaluator/template_validation/content/test_template_content_validator.py
@@ -294,12 +294,19 @@ class TemplateContentValidatorTest(ValidatorTest):
     def _execute_and_assert_with_fault_result(self,
                                               template,
                                               status_code,
-                                              def_temps={}):
+                                              def_temps=None):
 
+        if def_temps is None:
+            def_temps = {}
         result = validator.content_validation(template, def_temps)
         self._assert_fault_result(result, status_code)
 
-    def _execute_and_assert_with_correct_result(self, template, def_temps={}):
+    def _execute_and_assert_with_correct_result(self,
+                                                template,
+                                                def_temps=None):
+
+        if def_temps is None:
+            def_temps = {}
 
         result = validator.content_validation(template, def_temps)
         self._assert_correct_result(result)