diff --git a/addons/auth_crypt/auth_crypt.py b/addons/auth_crypt/auth_crypt.py
index d0a4fda9632..08dd156a603 100644
--- a/addons/auth_crypt/auth_crypt.py
+++ b/addons/auth_crypt/auth_crypt.py
@@ -143,7 +143,7 @@ class res_users(osv.osv):
         cr.execute('SELECT password, password_crypt FROM res_users WHERE id=%s AND active', (uid,))
         if cr.rowcount:
             stored_password, stored_password_crypt = cr.fetchone()
-            if password and not stored_password_crypt:
+            if stored_password and not stored_password_crypt:
                 salt = gen_salt()
                 stored_password_crypt = md5crypt(stored_password, salt)
                 cr.execute("UPDATE res_users SET password='', password_crypt=%s WHERE id=%s", (stored_password_crypt, uid))
@@ -151,14 +151,15 @@ class res_users(osv.osv):
             return super(res_users, self).check_credentials(cr, uid, password)
         except openerp.exceptions.AccessDenied:
             # check md5crypt
-            if stored_password_crypt[:len(magic_md5)] == magic_md5:
-                salt = stored_password_crypt[len(magic_md5):11]
-                if stored_password_crypt == md5crypt(password, salt):
-                    return
-            elif stored_password_crypt[:len(magic_md5)] == magic_sha256:
-                salt = stored_password_crypt[len(magic_md5):11]
-                if stored_password_crypt == md5crypt(password, salt):
-                    return
+            if stored_password_crypt:
+                if stored_password_crypt[:len(magic_md5)] == magic_md5:
+                    salt = stored_password_crypt[len(magic_md5):11]
+                    if stored_password_crypt == md5crypt(password, salt):
+                        return
+                elif stored_password_crypt[:len(magic_md5)] == magic_sha256:
+                    salt = stored_password_crypt[len(magic_md5):11]
+                    if stored_password_crypt == md5crypt(password, salt):
+                        return
             # Reraise password incorrect
             raise