diff --git a/lib/shared/mention-utils.js b/lib/shared/mention-utils.js
--- a/lib/shared/mention-utils.js
+++ b/lib/shared/mention-utils.js
@@ -123,10 +123,7 @@
   chatNamePrefix: string,
 ): $ReadOnlyArray<MentionTypeaheadChatSuggestionItem> {
   const result = [];
-  const threadIDs =
-    chatNamePrefix.length === 0
-      ? chatSearchIndex.entries
-      : chatSearchIndex.getSearchResults(chatNamePrefix);
+  const threadIDs = chatSearchIndex.getSearchResults(chatNamePrefix);
   for (const threadID of threadIDs) {
     if (!chatMentionCandidates[threadID]) {
       continue;
diff --git a/lib/shared/sentence-prefix-search-index.js b/lib/shared/sentence-prefix-search-index.js
--- a/lib/shared/sentence-prefix-search-index.js
+++ b/lib/shared/sentence-prefix-search-index.js
@@ -9,11 +9,8 @@
 const tokenize = new Tokenizer().re(/\S+/);
 
 class SentencePrefixSearchIndex extends SearchIndex {
-  entries: Set<string>;
-
   constructor() {
     super(tokenize);
-    this.entries = new Set();
   }
 
   addEntry(id: string, rawText: string) {
@@ -22,7 +19,6 @@
       const value = rawText.slice(keyword.index).toLowerCase();
       this.addAllPrefixes(id, value);
     }
-    this.entries.add(id);
   }
 
   getSearchResults(query: string): string[] {