diff --git a/app/controllers/groups/members_controller.rb b/app/controllers/groups/members_controller.rb
index e6d95a95c..786c9bc3a 100644
--- a/app/controllers/groups/members_controller.rb
+++ b/app/controllers/groups/members_controller.rb
@@ -38,13 +38,13 @@ class Groups::MembersController < Groups::BaseController
   end
 
   def add
-    if params['user_id'].present?
-      @user = User.find_by_uname(params['user_id'])
-      if parent.add_member(@user, params[:role])
-        flash[:notice] = t("flash.members.successfully_added")
-      else
-        flash[:error] = t("flash.members.error_in_adding")
-      end
+    @user = User.find_by_uname(params[:user_id])
+    if !@user
+      flash[:error] = t("flash.collaborators.wrong_user", :uname => params[:user_id])
+    elsif parent.add_member(@user, params[:role])
+      flash[:notice] = t("flash.members.successfully_added")
+    else
+      flash[:error] = t("flash.members.error_in_adding")
     end
     redirect_to group_members_path(parent)
   end
diff --git a/app/controllers/platforms/platforms_controller.rb b/app/controllers/platforms/platforms_controller.rb
index cd2de9147..43319bb55 100644
--- a/app/controllers/platforms/platforms_controller.rb
+++ b/app/controllers/platforms/platforms_controller.rb
@@ -96,12 +96,13 @@ class Platforms::PlatformsController < Platforms::BaseController
   end
 
   def add_member
-    if member = User.where(:id => params[:member_id]).first
-      if @platform.add_member(member)
-        flash[:notice] = t('flash.platform.members.successfully_added', :name => member.uname)
-      else
-        flash[:error] = t('flash.platform.members.error_in_adding', :name => member.uname)
-      end
+    member = User.where(:id => params[:member_id]).first
+    if !member
+      flash[:error] = t("flash.collaborators.wrong_user", :uname => params[:member_id])
+    elsif @platform.add_member(member)
+      flash[:notice] = t('flash.platform.members.successfully_added', :name => member.uname)
+    else
+      flash[:error] = t('flash.platform.members.error_in_adding', :name => member.uname)
     end
     redirect_to members_platform_url(@platform)
   end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index ce2f6a1be..da2c83dc8 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -148,6 +148,7 @@ en:
       group_already_added: Group already added
       successfully_added: Member %s successfully added
       error_in_adding: Member %s adding error
+      wrong_user: User with nickname '%{uname}' not found!
 
     blob:
       successfully_updated: File '%{name}' successfully updated
diff --git a/config/locales/ru.yml b/config/locales/ru.yml
index 927c12501..482fa06b5 100644
--- a/config/locales/ru.yml
+++ b/config/locales/ru.yml
@@ -148,6 +148,7 @@ ru:
       group_already_added: Группа уже добавлена
       successfully_added: Участник %s успешно добавлен
       error_in_adding: Ошибка при добавлении участника %s
+      wrong_user: Пользователь с ником '%{uname}' не найден.
 
     blob:
       successfully_updated: Файл '%{name}' успешно обновлен