diff --git a/r2/r2/controllers/api.py b/r2/r2/controllers/api.py
index efd6fd530..fa2a953ab 100755
--- a/r2/r2/controllers/api.py
+++ b/r2/r2/controllers/api.py
@@ -2885,22 +2885,22 @@ class ApiController(RedditController, OAuth2ResourceController):
     @validatedForm(VUser(),
                    VModhash(),
                    client=VOAuth2ClientDeveloper(),
-                   account=VExistingUnameNotSelf('name'))
+                   account=VExistingUname('name'))
     @api_doc(api_section.apps)
     def POST_adddeveloper(self, form, jquery, client, account):
         if not client:
-            form.set_html('.status', _('error'))
             return
         if form.has_errors('name', errors.USER_DOESNT_EXIST, errors.NO_USER):
-            form.set_html('.status', _('invalid user'))
             return
         if client.has_developer(account):
-            form.set_html('.status', _('already added'))
+            c.errors.add(errors.DEVELOPER_ALREADY_ADDED, field='name')
+            form.set_error(errors.DEVELOPER_ALREADY_ADDED, 'name')
             return
         try:
             client.add_developer(account)
         except OverflowError:
-            form.set_html('.status', _('too many developers'))
+            c.errors.add(errors.TOO_MANY_DEVELOPERS, field='')
+            form.set_error(errors.TOO_MANY_DEVELOPERS, '')
             return
 
         form.set_html('.status', _('developer added'))
diff --git a/r2/r2/controllers/errors.py b/r2/r2/controllers/errors.py
index f55d0fc22..3764911b6 100644
--- a/r2/r2/controllers/errors.py
+++ b/r2/r2/controllers/errors.py
@@ -101,6 +101,8 @@ error_list = dict((
         ('NO_OTP_SECRET', _('you must enable two-factor authentication')),
         ('NOT_SUPPORTED', _('this feature is not supported')),
         ('BAD_IMAGE', _('image problem')),
+        ('DEVELOPER_ALREADY_ADDED', _('already added')),
+        ('TOO_MANY_DEVELOPERS', _('too many developers')),
     ))
 errors = Storage([(e, e) for e in error_list.keys()])
 
diff --git a/r2/r2/controllers/validator/validator.py b/r2/r2/controllers/validator/validator.py
index 3c41cca1b..91ce5dbdf 100644
--- a/r2/r2/controllers/validator/validator.py
+++ b/r2/r2/controllers/validator/validator.py
@@ -1097,20 +1097,14 @@ class VExistingUname(VRequired):
                 return Account._by_name(name)
             except NotFound:
                 self.error(errors.USER_DOESNT_EXIST)
-        self.error()
+        else:
+            self.error()
 
     def param_docs(self):
         return {
             self.param: _('the name of an existing user')
         }
 
-class VExistingUnameNotSelf(VExistingUname):
-    def run(self, name):
-        user = super(VExistingUnameNotSelf, self).run(name)
-        if not user or user == c.user:
-            self.error()
-        return user
-
 class VMessageRecipient(VExistingUname):
     def run(self, name):
         if not name:
diff --git a/r2/r2/templates/prefapps.html b/r2/r2/templates/prefapps.html
index 73d77ea98..7daa7a2ba 100644
--- a/r2/r2/templates/prefapps.html
+++ b/r2/r2/templates/prefapps.html
@@ -139,6 +139,11 @@
                 <input type="hidden" name="client_id" value="${app._id}" />
                 ${_('add developer')}: <input name="name">
                 <br>
+                ${error_field('TOO_MANY_DEVELOPERS', '')}
+                ${error_field('OAUTH2_INVALID_CLIENT', 'client_id')}
+                ${error_field('DEVELOPER_ALREADY_ADDED', 'name')}
+                ${error_field('USER_DOESNT_EXIST', 'name')}
+                ${error_field('NO_USER', 'name')}
                 <span class="status"></span>
               </form>
             </td>