diff --git a/heat/engine/parameters.py b/heat/engine/parameters.py
index b3f6b8efe7..27fbd44568 100644
--- a/heat/engine/parameters.py
+++ b/heat/engine/parameters.py
@@ -340,7 +340,10 @@ class CommaDelimitedListParam(Parameter, collections.Sequence):
 
     def __init__(self, name, schema, value=None):
         super(CommaDelimitedListParam, self).__init__(name, schema, value)
-        self.parsed = self.parse(self.user_value or self.default())
+        if self.has_value():
+            self.parsed = self.parse(self.user_value or self.default())
+        else:
+            self.parsed = []
 
     def parse(self, value):
         # only parse when value is not already a list
@@ -357,7 +360,10 @@ class CommaDelimitedListParam(Parameter, collections.Sequence):
         return value
 
     def value(self):
-        return self.parsed
+        if self.has_value():
+            return self.parsed
+
+        raise exception.UserParameterMissing(key=self.name)
 
     def __len__(self):
         '''Return the length of the list.'''
@@ -382,7 +388,10 @@ class JsonParam(Parameter):
 
     def __init__(self, name, schema, value=None):
         super(JsonParam, self).__init__(name, schema, value)
-        self.parsed = self.parse(self.user_value or self.default())
+        if self.has_value():
+            self.parsed = self.parse(self.user_value or self.default())
+        else:
+            self.parsed = {}
 
     def parse(self, value):
         try:
@@ -397,7 +406,10 @@ class JsonParam(Parameter):
         return value
 
     def value(self):
-        return self.parsed
+        if self.has_value():
+            return self.parsed
+
+        raise exception.UserParameterMissing(key=self.name)
 
     def __getitem__(self, key):
         return self.parsed[key]
diff --git a/heat/tests/test_parameters.py b/heat/tests/test_parameters.py
index 57c0ec62fa..cd1c065361 100644
--- a/heat/tests/test_parameters.py
+++ b/heat/tests/test_parameters.py
@@ -363,12 +363,24 @@ class ParameterTest(testtools.TestCase):
                                 self.new_parameter, 'bo', schema, 'foo')
         self.assertIn("Unrecognized value 'foo'", six.text_type(err))
 
-    def test_missing_param(self):
+    def test_missing_param_str(self):
         '''Test missing user parameter.'''
         self.assertRaises(exception.UserParameterMissing,
                           self.new_parameter, 'p',
                           {'Type': 'String'})
 
+    def test_missing_param_list(self):
+        '''Test missing user parameter.'''
+        self.assertRaises(exception.UserParameterMissing,
+                          self.new_parameter, 'p',
+                          {'Type': 'CommaDelimitedList'})
+
+    def test_missing_param_map(self):
+        '''Test missing user parameter.'''
+        self.assertRaises(exception.UserParameterMissing,
+                          self.new_parameter, 'p',
+                          {'Type': 'Json'})
+
     def test_param_name_in_error_message(self):
         schema = {'Type': 'String',
                   'AllowedPattern': '[a-z]*'}
diff --git a/heat_integrationtests/functional/test_autoscaling.py b/heat_integrationtests/functional/test_autoscaling.py
index 15b318bdac..60fa66fea3 100644
--- a/heat_integrationtests/functional/test_autoscaling.py
+++ b/heat_integrationtests/functional/test_autoscaling.py
@@ -70,7 +70,7 @@ parameters:
   InstanceType: {type: string}
   SecurityGroups: {type: comma_delimited_list}
   UserData: {type: string}
-  Tags: {type: comma_delimited_list}
+  Tags: {type: comma_delimited_list, default: "x,y"}
 
 resources:
   random1:
@@ -93,7 +93,7 @@ parameters:
   InstanceType: {type: string}
   SecurityGroups: {type: comma_delimited_list}
   UserData: {type: string}
-  Tags: {type: comma_delimited_list}
+  Tags: {type: comma_delimited_list, default: "x,y"}
 
 resources:
   random1:
@@ -612,7 +612,7 @@ parameters:
   InstanceType: {type: string}
   SecurityGroups: {type: comma_delimited_list}
   UserData: {type: string}
-  Tags: {type: comma_delimited_list}
+  Tags: {type: comma_delimited_list, default: "x,y"}
 
 resources:
 outputs: