diff --git a/src/urllib3/connection.py b/src/urllib3/connection.py
index d2d456fb3c..9066e6ade4 100644
--- a/src/urllib3/connection.py
+++ b/src/urllib3/connection.py
@@ -215,7 +215,7 @@ def putrequest(self, method, url, *args, **kwargs):
 
     def putheader(self, header, *values):
         """"""
-        if SKIP_HEADER not in values:
+        if not any(isinstance(v, str) and v == SKIP_HEADER for v in values):
             _HTTPConnection.putheader(self, header, *values)
         elif six.ensure_str(header.lower()) not in SKIPPABLE_HEADERS:
             raise ValueError(