diff --git a/rattail_fabric/python.py b/rattail_fabric/python.py
index 71fafbe..3192d0f 100644
--- a/rattail_fabric/python.py
+++ b/rattail_fabric/python.py
@@ -58,13 +58,13 @@ def pip(*packages, **kwargs):
     """
     Install one or more packages via ``pip install``.
     """
-    upgrade_strategy = kwargs.pop('upgrade_strategy', '')
+    upgrade_strategy = kwargs.pop('upgrade_strategy', None)
     if upgrade_strategy:
         upgrade_strategy = '--upgrade-strategy {}'.format(upgrade_strategy)
     if kwargs:
         abort("Unknown kwargs for pip(): {}".format(kwargs))
     packages = ["'{}'".format(p) for p in packages]
-    sudo('pip install --upgrade {} {}'.format(upgrade_strategy, ' '.join(packages)))
+    sudo('pip install --upgrade {} {}'.format(upgrade_strategy or '', ' '.join(packages)))
 
 
 def install_virtualenvwrapper(workon_home=None, user='root', use_apt=False):