diff --git a/orchestra/apps/systemusers/forms.py b/orchestra/apps/systemusers/forms.py
index 04cf3300..78318565 100644
--- a/orchestra/apps/systemusers/forms.py
+++ b/orchestra/apps/systemusers/forms.py
@@ -62,6 +62,7 @@ class SystemUserFormMixin(object):
         if home and self.MOCK_USERNAME in home:
             username = self.cleaned_data.get('username', '')
             self.cleaned_data['home'] = home.replace(self.MOCK_USERNAME, username)
+        self.instance.validate_home(self.cleaned_data, self.account)
 
 
 class SystemUserCreationForm(SystemUserFormMixin, UserCreationForm):
diff --git a/orchestra/apps/systemusers/models.py b/orchestra/apps/systemusers/models.py
index b2264ee3..5f03532c 100644
--- a/orchestra/apps/systemusers/models.py
+++ b/orchestra/apps/systemusers/models.py
@@ -88,6 +88,29 @@ class SystemUser(models.Model):
                     'directory': directory_error,
                 })
     
+    def validate_home(self, data, account):
+        """ validates home based on account and data['shell'] """
+        if not 'username' in data and not self.pk:
+            # other validation will have raised for required username
+            return
+        user = type(self)(
+            username=data.get('username') or self.username,
+            shell=data.get('shell') or self.shell,
+        )
+        if 'home' in data and data['home']:
+            home = data['home'].rstrip('/')
+            user_home = user.get_home().rstrip('/')
+            account_home = account.main_systemuser.get_home().rstrip('/')
+            if user.has_shell:
+                if home != user_home:
+                    raise ValidationError({
+                        'home': _("Not a valid home directory.")
+                    })
+            elif home not in (user_home, account_home):
+                raise ValidationError({
+                    'home': _("Not a valid home directory.")
+                })
+    
     def set_password(self, raw_password):
         self.password = make_password(raw_password)
     
diff --git a/orchestra/apps/systemusers/serializers.py b/orchestra/apps/systemusers/serializers.py
index 86e0d690..a7e76b1e 100644
--- a/orchestra/apps/systemusers/serializers.py
+++ b/orchestra/apps/systemusers/serializers.py
@@ -40,17 +40,7 @@ class SystemUserSerializer(AccountSerializerMixin, HyperlinkedModelSerializer):
             username=attrs.get('username') or self.object.username,
             shell=attrs.get('shell') or self.object.shell,
         )
-        if 'home' in attrs and attrs['home']:
-            home = attrs['home'].rstrip('/') + '/'
-            if user.has_shell:
-                if home != user.get_base_home():
-                    raise ValidationError({
-                        'home': _("Not a valid home directory.")
-                    })
-            elif home not in (user.get_home(), self.account.main_systemuser.get_home()):
-                raise ValidationError({
-                    'home': _("Not a valid home directory.")
-                })
+        user.validate_home(attrs, self.account)
         return attrs
     
     def validate_password(self, attrs, source):