diff --git a/AUTHORS.txt b/AUTHORS.txt
index 0beb601b..ce7c1d60 100644
--- a/AUTHORS.txt
+++ b/AUTHORS.txt
@@ -18,7 +18,7 @@ andviro (@andviro)
 Mike Gilbert (@floppym) <floppym@gentoo.org>
 Aaron Meurer (@asmeurer) <asmeurer@gmail.com>
 Lubos Trilety <ltrilety@redhat.com>
-Akinori Hattori (@hattya)
+Akinori Hattori (@hattya) <hattya@gmail.com>
 srusskih (@srusskih)
 Steven Silvester (@blink1073)
 Colin Duquesnoy (@ColinDuquesnoy) <colin.duquesnoy@gmail.com>
diff --git a/jedi/evaluate/sys_path.py b/jedi/evaluate/sys_path.py
index d09cfec8..852210bd 100644
--- a/jedi/evaluate/sys_path.py
+++ b/jedi/evaluate/sys_path.py
@@ -15,9 +15,13 @@ def get_sys_path():
         if not venv:
             return
         venv = os.path.abspath(venv)
-        p = os.path.join(
-            venv, 'lib', 'python%d.%d' % sys.version_info[:2], 'site-packages')
-        sys_path.insert(0, p)
+        if os.name == 'nt':
+            p = os.path.join(venv, 'lib', 'site-packages')
+        else:
+            p = os.path.join(venv, 'lib', 'python%d.%d' % sys.version_info[:2],
+                             'site-packages')
+        if p not in sys_path:
+            sys_path.insert(0, p)
 
     check_virtual_env(sys.path)
     return [p for p in sys.path if p != ""]