diff --git a/eq-author/src/components/AnswerContent/AnswerProperties/TextFieldProperties.js b/eq-author/src/components/AnswerContent/AnswerProperties/TextFieldProperties.js
index a95fb1e8e7..77b704f7b8 100644
--- a/eq-author/src/components/AnswerContent/AnswerProperties/TextFieldProperties.js
+++ b/eq-author/src/components/AnswerContent/AnswerProperties/TextFieldProperties.js
@@ -75,6 +75,7 @@ const TextFieldProperties = ({
             value={maxLength}
             onBlur={() => onUpdateMaxLength(maxLength)}
             onChange={({ value }) => setMaxLength(value)}
+            invalid={errors.length > 0}
             data-test="limitCharacterInput"
           />
         </InlineField>