diff --git a/src/edu/caltech/cs2/interfaces/ITrieMap.java b/src/edu/caltech/cs2/interfaces/ITrieMap.java
index 5ef601f53f4a425c54bfb5cf5e6b62fe900b1c1b..aa6e84707b6e828ed0c1201f59b7946bc865b1b7 100644
--- a/src/edu/caltech/cs2/interfaces/ITrieMap.java
+++ b/src/edu/caltech/cs2/interfaces/ITrieMap.java
@@ -13,7 +13,7 @@ public interface ITrieMap<A, K extends Iterable<A>, V> extends IDictionary<K, V>
      * @param prefix the prefix to search for in the trie
      * @return the values corresponding to the keys starting with the given prefix
      */
-    public IDeque<V> getCompletions(K prefix);
+    public ICollection<V> getCompletions(K prefix);
 
     /**
      * Removes all elements from the trie.