diff --git a/pipenv/cli/options.py b/pipenv/cli/options.py
index 2d073288..cf9daa19 100644
--- a/pipenv/cli/options.py
+++ b/pipenv/cli/options.py
@@ -93,10 +93,7 @@ def index_option(f):
 def extra_index_option(f):
     def callback(ctx, param, value):
         state = ctx.ensure_object(State)
-        if isinstance(value, (tuple, list)):
-            state.extra_index_urls.extend(list(value))
-        else:
-            state.extra_index_urls.append(value)
+        state.extra_index_urls.extend(list(value))
         return value
     return option("--extra-index-url", multiple=True, expose_value=False,
         help=u"URLs to the extra PyPI compatible indexes to query for package lookups.",
diff --git a/pipenv/vendor/requirementslib/__init__.py b/pipenv/vendor/requirementslib/__init__.py
index 8eb90d54..0faea40b 100644
--- a/pipenv/vendor/requirementslib/__init__.py
+++ b/pipenv/vendor/requirementslib/__init__.py
@@ -1,5 +1,5 @@
 # -*- coding=utf-8 -*-
-__version__ = '1.1.6.dev0'
+__version__ = '1.1.7.dev0'
 
 
 from .exceptions import RequirementError
diff --git a/pipenv/vendor/vendor.txt b/pipenv/vendor/vendor.txt
index 9b6d7bea..d1667eeb 100644
--- a/pipenv/vendor/vendor.txt
+++ b/pipenv/vendor/vendor.txt
@@ -27,7 +27,7 @@ requests==2.19.1
     idna==2.7
     urllib3==1.23
     certifi==2018.8.24
-requirementslib==1.1.5
+requirementslib==1.1.6
     attrs==18.1.0
     distlib==0.2.7
     packaging==17.1