diff --git a/bin/addons/__init__.py b/bin/addons/__init__.py
index 6e5bd3b567b..dcb8f3a2eb0 100644
--- a/bin/addons/__init__.py
+++ b/bin/addons/__init__.py
@@ -47,8 +47,8 @@ import logging
 
 logger = netsvc.Logger()
 
-_ad = os.path.abspath(opj(tools.config['root_path'], 'addons'))     # default addons path (base)
-ad_paths= map(lambda m: os.path.abspath(m.strip()),tools.config['addons_path'].split(','))
+_ad = os.path.abspath(opj(tools.ustr(tools.config['root_path']), u'addons'))     # default addons path (base)
+ad_paths= map(lambda m: os.path.abspath(tools.ustr(m.strip())), tools.config['addons_path'].split(','))
 
 sys.path.insert(1, _ad)
 
diff --git a/bin/tools/misc.py b/bin/tools/misc.py
index 88f06749f90..390be6b7837 100644
--- a/bin/tools/misc.py
+++ b/bin/tools/misc.py
@@ -262,7 +262,7 @@ def file_open(name, mode="r", subdir='addons', pathinfo=False):
             return fo
     if os.path.splitext(name)[1] == '.rml':
         raise IOError, 'Report %s doesn\'t exist or deleted : ' %str(name)
-    raise IOError, 'File not found : '+str(name)
+    raise IOError, 'File not found : %s' % name
 
 
 #----------------------------------------------------------