diff --git a/addons/website_forum/static/src/css/website_forum.css b/addons/website_forum/static/src/css/website_forum.css
index 4d64309d8ff..0e153f79ece 100644
--- a/addons/website_forum/static/src/css/website_forum.css
+++ b/addons/website_forum/static/src/css/website_forum.css
@@ -5,7 +5,7 @@
     font-size: 160%;
     font-weight: bold;
     line-height: 12px; }
-  .vote .vote-up, .vote .vote-down {
+  .vote .vote_up, .vote .vote_down {
     font-size: 130%; }
 
 .author-box {
diff --git a/addons/website_forum/static/src/css/website_forum.sass b/addons/website_forum/static/src/css/website_forum.sass
index 999c66d6227..cd3784723c2 100644
--- a/addons/website_forum/static/src/css/website_forum.sass
+++ b/addons/website_forum/static/src/css/website_forum.sass
@@ -5,7 +5,7 @@
     font-size: 160%
     font-weight: bold
     line-height: 12px
-  .vote-up,.vote-down
+  .vote_up,.vote_down
     font-size: 130%
 
 .author-box