diff --git a/platypush/message/request/__init__.py b/platypush/message/request/__init__.py
index e8863263..127fd9f7 100644
--- a/platypush/message/request/__init__.py
+++ b/platypush/message/request/__init__.py
@@ -135,7 +135,10 @@ class Request(Message):
 
                 else:
                     try:
-                        parsed_value += prefix + eval(inner_expr)
+                        expanded_expr = eval(inner_expr)
+                        parsed_value += prefix
+                        if expanded_expr is not None:
+                            parsed_value += expanded_expr
                     except Exception as e:
                         logging.exception(e)
                         parsed_value += prefix + expr
diff --git a/platypush/plugins/google/maps.py b/platypush/plugins/google/maps.py
index 55eb7f5f..a5ca675e 100644
--- a/platypush/plugins/google/maps.py
+++ b/platypush/plugins/google/maps.py
@@ -44,7 +44,11 @@ class GoogleMapsPlugin(GooglePlugin):
                         address['postal_code'] = addr_component['long_name']
 
             if 'address' in address and 'street_number' in address:
-                address['address'] += ' ' + address['street_number']
+                address['address'] = '{}{}{}'.format(
+                    (address['address'] or ''),
+                    (' ' if address['street_number'] else ''),
+                    (address['street_number'] or ''))
+
                 del(address['street_number'])
 
         return Response(output=address)