diff --git a/frontend/src/ts/input/handlers/insert-text.ts b/frontend/src/ts/input/handlers/insert-text.ts
index 953d0938ae46..23d7bff011b8 100644
--- a/frontend/src/ts/input/handlers/insert-text.ts
+++ b/frontend/src/ts/input/handlers/insert-text.ts
@@ -68,7 +68,7 @@ export async function onInsertText(options: OnInsertTextParams): Promise<void> {
     // make sure to not call TestInput.input.syncWithInputElement in here
     // it will be updated later in the body of onInsertText
     const { inputValue } = getInputElementValue();
-    setInputElementValue(inputValue.slice(0, -options.data.length));
+    setInputElementValue(inputValue.slice(0, -1));
     for (let i = 0; i < options.data.length; i++) {
       const char = options.data[i] as string;