diff --git a/ldapom/connection.py b/ldapom/connection.py
index b6fdda0..66ac071 100644
--- a/ldapom/connection.py
+++ b/ldapom/connection.py
@@ -402,20 +402,16 @@ def save(self, entry):
             raise error.LDAPomError("Cannot save without attributes "
                     "previously fetched or set.")
 
-        # Temporary attribute set that will contain deleted attributes as
-        # LDAPAttribute objects without any values.
-        save_attributes = entry.attributes.copy()
-        if entry_exists:
-            deleted_attribute_names = entry._old_attribute_names.difference(
-                    [a.name for a in entry.attributes])
-            for name in deleted_attribute_names:
-                attribute_type = self.get_attribute_type(name)
-                save_attributes.add(attribute_type(name))
-
-        if not entry_exists:
-            # Don't try to save empty attributes as this fails if the entry
-            # does not exist on the server yet.
-            save_attributes = filter(lambda a: a._values > 0, save_attributes)
+        # remove empty attributes as ldap_add_ext_s can't handle them
+        is_empty = lambda attr: len(attr._get_ldap_values()) > 0
+        save_attributes = set(filter(is_empty, entry.attributes))
+
+        # add deleted attributes as empty attributes (LDAPAttribute objects without any values)
+        deleted_attribute_names = entry._old_attribute_names.difference(
+                [a.name for a in save_attributes])
+        for name in deleted_attribute_names:
+            attribute_type = self.get_attribute_type(name)
+            save_attributes.add(attribute_type(name))
 
         # Keep around references to pointers to owned memory with data that is
         # still needed.
@@ -444,7 +440,7 @@ def save(self, entry):
             mods[i] = mod
         mods[len(save_attributes)] = ffi.NULL
 
-        if entry_exists:
+        if entry.exists():
             err = ldap.ldap_modify_ext_s(self._ld,
                     compat._encode_utf8(entry.dn),
                     mods,
diff --git a/ldapom/entry.py b/ldapom/entry.py
index 75df7f2..7072c42 100644
--- a/ldapom/entry.py
+++ b/ldapom/entry.py
@@ -25,7 +25,7 @@ def __init__(self, connection, dn, attributes=None):
         super(LDAPEntry, self).__setattr__('attributes', set(attributes)
                 if attributes is not None else None)
         super(LDAPEntry, self).__setattr__('_old_attribute_names',
-                set([a.name for a in attributes]) if attributes else None)
+                set([a.name for a in attributes]) if attributes else set())
 
     ## Expose dn as a ready-only property
     dn = property(lambda self: self._dn)