diff --git a/src/libstd/hashmap.rs b/src/libstd/hashmap.rs
index 0b6bf339d7e..7d55947e818 100644
--- a/src/libstd/hashmap.rs
+++ b/src/libstd/hashmap.rs
@@ -719,7 +719,7 @@ impl<T:Hash + Eq> HashSet<T> {
     }
 
     /// Visit all elements in arbitrary order
-    /// FIXME: Remove when all callers are converted
+    /// FIXME: #6978: Remove when all callers are converted
     pub fn each(&self, f: &fn(&T) -> bool) -> bool {
         self.iter().advance(f)
     }