diff --git a/src/nucleus/response/common.py b/src/nucleus/response/common.py
index fb1d537..0748f81 100644
--- a/src/nucleus/response/common.py
+++ b/src/nucleus/response/common.py
@@ -12,11 +12,13 @@ class Response:
         self.code = 200
         self.phrase = 'Success'
         self.version = 'HTTP/1.1'
-        self.headers = {}
-        self.content_type = "text/plain"
+        self.headers = {
+            'Content-Type': 'text/plain'
+        }
+        self.__content_type = 'text/plain'
         for key in kwargs:
-            if key in self.__dict__:
-                setattr(self, key, kwargs[key])
+            if key in ['content_type', 'mimetype']:
+                self.__content_type = kwargs[key]
 
     def __call__(self):
         status = ' '.join([self.version, str(self.code), self.phrase])
@@ -27,7 +29,6 @@ class Response:
         ])
         return raw
 
-    def __iter__(self):
-        pass
-    def __next__(self):
-        pass
+    @property
+    def content_type(self):
+        return self.__content_type
diff --git a/src/nucleus/response/stream.py b/src/nucleus/response/stream.py
index df59f42..0a89f80 100644
--- a/src/nucleus/response/stream.py
+++ b/src/nucleus/response/stream.py
@@ -51,6 +51,7 @@ def str_next(instance):
     if instance.position == 'headers':
         instance.position = 'body'
         raw = b''
+        response.headers['Content-Type'] = response.content_type
         for key in response.headers:
             value = response.headers[key]
             raw += key.encode() + b' ' + value.encode() + crlf