diff --git a/ts/editor/cloze.ts b/ts/editor/cloze.ts
index 9d3be3530..8a3a6491a 100644
--- a/ts/editor/cloze.ts
+++ b/ts/editor/cloze.ts
@@ -17,11 +17,15 @@ function getCurrentHighestCloze(increment: boolean): number {
     let highest = 0;
 
     forEditorField([], (field) => {
-        const matches = field.editingArea.editable.fieldHTML.matchAll(clozePattern);
-        highest = Math.max(
-            highest,
-            ...[...matches].map((match: RegExpMatchArray): number => Number(match[1]))
-        );
+        const fieldHTML = field.editingArea.editable.fieldHTML;
+        const matches: number[] = [];
+        let match: RegExpMatchArray | null = null;
+
+        while ((match = clozePattern.exec(fieldHTML))) {
+            matches.push(Number(match[1]));
+        }
+
+        highest = Math.max(highest, ...matches);
     });
 
     if (increment) {
diff --git a/ts/tsconfig.json b/ts/tsconfig.json
index 63afaad58..bc98946fd 100644
--- a/ts/tsconfig.json
+++ b/ts/tsconfig.json
@@ -3,14 +3,7 @@
     "compilerOptions": {
         "target": "es6",
         "module": "es6",
-        "lib": [
-            "es2017",
-            "es2020.string",
-            "es2019.array",
-            "es2018.promise",
-            "dom",
-            "dom.iterable"
-        ],
+        "lib": ["es2017", "es2019.array", "es2018.promise", "dom", "dom.iterable"],
         "baseUrl": ".",
         "paths": {
             "anki/*": ["../bazel-bin/ts/lib/*"],