diff --git a/haddock-api/resources/html/Classic.theme/xhaddock.css b/haddock-api/resources/html/Classic.theme/xhaddock.css
index 19dc28ec66df52b4278bbf3bf9e5c89e4596fb2a..1bf668e96ea93feb2bd80dcd31f0585b9d3814ef 100644
--- a/haddock-api/resources/html/Classic.theme/xhaddock.css
+++ b/haddock-api/resources/html/Classic.theme/xhaddock.css
@@ -285,6 +285,7 @@ div.top h5 {
 	padding: 0 8px 2px 5px;
 	margin-right: -3px;
 	background-color: #f0f0f0;
+	-moz-user-select: none;
 }
 
 div.subs {
diff --git a/haddock-api/resources/html/Ocean.std-theme/ocean.css b/haddock-api/resources/html/Ocean.std-theme/ocean.css
index 3bfc8982ac0f23d937763166d2c44c6c252bdbef..8d3f91a9ca4c554e227208cd3f62b45680be1072 100644
--- a/haddock-api/resources/html/Ocean.std-theme/ocean.css
+++ b/haddock-api/resources/html/Ocean.std-theme/ocean.css
@@ -394,6 +394,7 @@ div#style-menu-holder {
   background: #f0f0f0;
   padding: 0 0.5em 0.2em;
   margin: 0 -0.5em 0 0;
+  -moz-user-select: none;
 }
 #interface .src .selflink {
   border-left: 1px solid #919191;