diff --git a/README.python3 b/README.python3
new file mode 100644
index 0000000000..6f34cd75e3
--- /dev/null
+++ b/README.python3
@@ -0,0 +1,29 @@
+Efforts to port calibre to python 3 are ongoing. calibre can be run
+using python3 under Linux. To do so, install python 3, checkout calibre
+from source with
+
+    git clone git@github.com:kovidgoyal/calibre.git && cd calibre
+
+Then, setup calibre to run under python2, with:
+
+    python2 setup.py bootstrap
+
+Check that calibre works, with:
+
+    python2 run-local calibre
+
+Now build the calibre C extensions for python 3 with:
+
+    CALIBRE_PY3_PORT=1 python3 setup.py build
+
+You should now be able to run the calibre test suite using:
+
+    python3 setup.py test
+
+And run calibre itself (which may not work) with:
+
+    python3 run-local calibre
+
+
+For the status of the port, and discussion of its design, see
+https://github.com/kovidgoyal/calibre/pull/870
diff --git a/setup/build.py b/setup/build.py
index 13c0e5c82c..41afd98173 100644
--- a/setup/build.py
+++ b/setup/build.py
@@ -217,8 +217,12 @@ def init_env():
 class Build(Command):
 
     short_description = 'Build calibre C/C++ extension modules'
-    DEFAULT_OUTPUTDIR = os.path.abspath(os.path.join(SRC, 'calibre', 'plugins'))
-    DEFAULT_BUILDDIR = os.path.abspath(os.path.join(os.path.dirname(SRC), 'build'))
+    if ispy3:
+        DEFAULT_OUTPUTDIR = os.path.abspath(os.path.join(SRC, 'calibre', 'plugins', '3'))
+        DEFAULT_BUILDDIR = os.path.abspath(os.path.join(os.path.dirname(SRC), 'build', '3'))
+    else:
+        DEFAULT_OUTPUTDIR = os.path.abspath(os.path.join(SRC, 'calibre', 'plugins'))
+        DEFAULT_BUILDDIR = os.path.abspath(os.path.join(os.path.dirname(SRC), 'build'))
 
     description = textwrap.dedent('''\
         calibre depends on several python extensions written in C/C++.
diff --git a/src/calibre/constants.py b/src/calibre/constants.py
index 80cbe9d223..78fb36860a 100644
--- a/src/calibre/constants.py
+++ b/src/calibre/constants.py
@@ -198,7 +198,10 @@ class Plugins(collections.Mapping):
     def load_plugin(self, name):
         if name in self._plugins:
             return
-        sys.path.insert(0, sys.extensions_location)
+        plugins_loc = sys.extensions_location
+        if ispy3:
+            plugins_loc = os.path.join(plugins_loc, '3')
+        sys.path.insert(0, plugins_loc)
         try:
             del sys.modules[name]
         except KeyError:
@@ -210,7 +213,7 @@ class Plugins(collections.Mapping):
             p = None
             plugin_err = unicode_type(err)
         self._plugins[name] = p, plugin_err
-        sys.path.remove(sys.extensions_location)
+        sys.path.remove(plugins_loc)
 
     def __iter__(self):
         return iter(self.plugins)