diff --git a/lib/shared/search-index.js b/lib/shared/search-index.js
--- a/lib/shared/search-index.js
+++ b/lib/shared/search-index.js
@@ -15,13 +15,16 @@
   ...
 };
 
+type TokenizeFunc = (str: string) => Token[];
+const defaultTokenize: TokenizeFunc = new Tokenizer().words();
+
 class SearchIndex {
   tokenize: (str: string) => Token[];
   fullTextIndex: { [token: string]: Set<string> };
   partialTextIndex: { [token: string]: Set<string> };
 
-  constructor() {
-    this.tokenize = new Tokenizer().words();
+  constructor(inputTokenize?: TokenizeFunc) {
+    this.tokenize = inputTokenize ?? defaultTokenize;
     this.fullTextIndex = {};
     this.partialTextIndex = {};
   }
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
@@ -4,12 +4,15 @@
 
 import SearchIndex from './search-index.js';
 
+// defaultTokenize used in SearchIndex splits on punctuation
+// We use this alternative because we only want to split on whitespace
+const tokenize = new Tokenizer().re(/\S+/);
+
 class SentencePrefixSearchIndex extends SearchIndex {
   entries: Set<string>;
 
   constructor() {
-    super();
-    this.tokenize = new Tokenizer().re(/\S+/);
+    super(tokenize);
     this.entries = new Set();
   }