diff --git a/openmc/universe.py b/openmc/universe.py
index 3ad17778e..f35b1d364 100644
--- a/openmc/universe.py
+++ b/openmc/universe.py
@@ -341,10 +341,11 @@ class Universe(UniverseBase):
         **kwargs
             Keyword arguments passed to :func:`matplotlib.pyplot.imshow`
 
-            .. versionadded:: 0.13.4
         outline : bool
             Whether outlines between color boundaries should be drawn
 
+            .. versionadded:: 0.13.4
+
         Returns
         -------
         matplotlib.image.AxesImage