diff --git a/aiohttp/web_request.py b/aiohttp/web_request.py
index 6a4737e7f2..e82b587574 100644
--- a/aiohttp/web_request.py
+++ b/aiohttp/web_request.py
@@ -409,7 +409,8 @@ def post(self):
                     out.add(field.name, ff)
                 else:
                     value = yield from field.read(decode=True)
-                    if content_type.startswith('text/'):
+                    if content_type is None or \
+                            content_type.startswith('text/'):
                         charset = field.get_charset(default='utf-8')
                         value = value.decode(charset)
                     out.add(field.name, value)