diff --git a/src/comp/middle/typeck.rs b/src/comp/middle/typeck.rs
index 8da317dc8ba0..aa636d9f2da0 100644
--- a/src/comp/middle/typeck.rs
+++ b/src/comp/middle/typeck.rs
@@ -2235,6 +2235,8 @@ fn check_expr(&@stmt_ctxt scx, &@ast::expr expr) {
 
             Pushdown::pushdown_expr(scx, pattern_ty, expr);
 
+            // FIXME: If all the the arms were ty_bot then the result should
+            // also be ty_bot. At the moment this doesn't seem to matter
             write::ty_only_fixup(scx, a.id, result_ty);
         }