diff --git a/components/style/invalidation/element/state_and_attributes.rs b/components/style/invalidation/element/state_and_attributes.rs
index 30521fb8c00..c4671b0011c 100644
--- a/components/style/invalidation/element/state_and_attributes.rs
+++ b/components/style/invalidation/element/state_and_attributes.rs
@@ -158,6 +158,14 @@ where
         // If we the visited state changed, we force a restyle here. Matching
         // doesn't depend on the actual visited state at all, so we can't look
         // at matching results to decide what to do for this case.
+        //
+        // TODO(emilio): This should be contains(), to avoid doing subtree
+        // restyles when adding or removing an href attribute, but invalidation
+        // for that case is broken right now (bug 1591987).
+        //
+        // This piece of code should be removed when
+        // layout.css.always-repaint-on-unvisited is true, since we cannot get
+        // into this situation in that case.
         if state_changes.intersects(ElementState::IN_VISITED_OR_UNVISITED_STATE) {
             trace!(" > visitedness change, force subtree restyle");
             // We can't just return here because there may also be attribute