expression, suru verb (irregular)
make certain; ensure; secure; strengthen
Used when taking action to turn something into a definite, reliable state. Often applied to plans, agreements, positions, or evidence.
契約を確かなものにするために、書面で確認した。
We confirmed it in writing to make the contract certain.
証拠を集めて、彼の無実を確かなものにした。
We gathered evidence and made his innocence certain.