diff --git a/CHANGES.txt b/CHANGES.txt
index 6a36d5bc9..edf52409d 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -2,6 +2,13 @@
 Chaco CHANGELOG
 ===============
 
+Release 4.7.0
+-------------
+
+Fixes
+
+* Update raise statement to be Python 3 compatible (PR #360)
+
 Release 4.6.1
 -------------
 
diff --git a/README.rst b/README.rst
index de32b362c..cc03dd97d 100644
--- a/README.rst
+++ b/README.rst
@@ -42,6 +42,7 @@ Features
 
 Prerequisites
 -------------
+Chaco is only supported on Python 2.7.x and Python >= 3.4.
 You must have the following libraries installed before building or installing
 Chaco:
 
diff --git a/chaco/plot.py b/chaco/plot.py
index f0ace7e6f..ff77eb0d4 100644
--- a/chaco/plot.py
+++ b/chaco/plot.py
@@ -173,8 +173,8 @@ def __init__(self, data=None, **kwtraits):
             elif type(data) in (ndarray, tuple, list):
                 self.data = ArrayPlotData(data)
             else:
-                raise ValueError, "Don't know how to create PlotData for data" \
-                                  "of type " + str(type(data))
+                raise ValueError("Don't know how to create PlotData for data "
+                                 "of type {0}".format(type(data)))
 
         if not self._title:
             self._title = PlotLabel(font="swiss 16", visible=False,