Psychological assessment is commonly conducted using either self-report measures or clinical interviews; the former are quick and easy to administer, and the later are more time consuming and require training. Self-report measures have been criticised for producing higher estimates of symptom and disorder presence relative to clinical interviews, with the assumption being that self-report measures are prone to Type 1 errors. Here, we introduce the use of ‘clinical checks’ within an existing self-report measure. These are brief supplementary questions intended to clarify and confirm initial responses, similar to what occurs in a clinical interview. Clinical checks were developed for the items of the International Grief Questionnaire (IGQ), a self-report measure of ICD-11 prolonged grief disorder (PGD). Data were collected as part of a community survey of mental health in Ukraine. Individual symptom endorsements for the IGQ significantly decreased with the use of clinical checks, and the percentage of the sample that met the ICD-11 diagnostic requirements for PGD fell from 13.6% to 10.2%, representing a 24.8% reduction of cases. The value and potential broader application of clinical checks are discussed.