diff --git a/docs/user/systems.rst b/docs/user/systems.rst
index 85ff096da..fb14dcae6 100644
--- a/docs/user/systems.rst
+++ b/docs/user/systems.rst
@@ -9,7 +9,7 @@ Pint Unit Registry has the concept of system, which is a group of units
 
     >>> import pint
     >>> ureg = pint.UnitRegistry(system='mks')
-    >>> pint.set_application_registry(ureg) 
+    >>> pint.set_application_registry(ureg)
     >>> ureg.default_system
     'mks'