diff --git a/modoboa/extensions/webmail/lib/signature.py b/modoboa/extensions/webmail/lib/signature.py
index 359801a1f..c90a00fa5 100644
--- a/modoboa/extensions/webmail/lib/signature.py
+++ b/modoboa/extensions/webmail/lib/signature.py
@@ -8,22 +8,22 @@ class EmailSignature(object):
     :param user: User object
     """
     def __init__(self, user):
-        self._sig = ""
+        self._sig = u""
         dformat = parameters.get_user(user, "EDITOR")
         content = parameters.get_user(user, "SIGNATURE")
         if len(content):
             getattr(self, "_format_sig_%s" % dformat)(content)
 
     def _format_sig_plain(self, content):
-        self._sig = """
+        self._sig = u"""
 ---
 %s""" % content
 
     def _format_sig_html(self, content):
         content = re.sub("\n", "<br/>", content)
-        self._sig = """<br/>
+        self._sig = u"""<br/>
 ---<br/>
 %s""" % content
 
-    def __repr__(self):
+    def __unicode__(self):
         return self._sig
diff --git a/modoboa/extensions/webmail/views.py b/modoboa/extensions/webmail/views.py
index 5f5088ac3..f39fa3576 100644
--- a/modoboa/extensions/webmail/views.py
+++ b/modoboa/extensions/webmail/views.py
@@ -344,14 +344,14 @@ def listmailbox(request, defmailbox="INBOX", update_session=True):
 def render_compose(request, form, posturl, email=None, insert_signature=False):
     editor = parameters.get_user(request.user, "EDITOR")
     if email is None:
-        body = ""
-        textheader = ""
+        body = u""
+        textheader = u""
     else:
         body = email.body
         textheader = email.textheader
     if insert_signature:
         signature = EmailSignature(request.user)
-        body += str(signature)
+        body += unicode(signature)
     randid = None
     if not "id" in request.GET:
         if "compose_mail" in request.session: