diff --git a/json2yamlschema.py b/json2yamlschema.py
index fd1bd96..02d0c19 100644
--- a/json2yamlschema.py
+++ b/json2yamlschema.py
@@ -26,6 +26,8 @@ def parser(json_data,indent):
         for key in json_data:
             write(indent + '  %s:' % key)
             parser(json_data[key], indent+'    ')
+    elif type(json_data) is None:
+        write(indent + 'type: string')
     elif type(json_data) is list:
         write(indent + 'type: array')
         write(indent + 'items:')
diff --git a/json2yamlschemaSORTED.py b/json2yamlschemaSORTED.py
index ed75f72..8223ccd 100644
--- a/json2yamlschemaSORTED.py
+++ b/json2yamlschemaSORTED.py
@@ -27,6 +27,8 @@ def parser(json_data):
         for key in json_data:
             d[key] = parser(json_data[key])
         return d
+    elif type(json_data) is None:
+        write(indent + 'type: string')
     elif type(json_data) is list:
         d['type'] = 'array'
         if len(json_data) != 0: