diff --git a/instaloader.py b/instaloader.py
index a901d02..6adcc3a 100755
--- a/instaloader.py
+++ b/instaloader.py
@@ -103,7 +103,7 @@ def copy_session(session: requests.Session) -> requests.Session:
     new = requests.Session()
     new.cookies = \
         requests.utils.cookiejar_from_dict(requests.utils.dict_from_cookiejar(session.cookies))
-    new.headers = session.headers
+    new.headers = session.headers.copy()
     return new