diff --git a/libwvdrmengine/oemcrypto/include/OEMCryptoCENC.h b/libwvdrmengine/oemcrypto/include/OEMCryptoCENC.h
index fd410044..ebd4b22e 100644
--- a/libwvdrmengine/oemcrypto/include/OEMCryptoCENC.h
+++ b/libwvdrmengine/oemcrypto/include/OEMCryptoCENC.h
@@ -4811,9 +4811,11 @@ OEMCryptoResult OEMCrypto_GetBootCertificateChain(
  * @param[in,out] public_key_size: on input, size of the caller's public_key
  *    buffer. On output, the number of bytes written into the buffer.
  * @param[out] public_key_signature: pointer to the buffer that receives the
- *    signature of the public key. If an OEM private key is unavailable, it is
- *    signed by the device private key; otherwise is signed by the OEM private
- *    key.
+ *    signature of the public key.
+ *    If an OEM private key is unavailable: it is signed by the device private
+ *    key. The signature must be in COSE_SIGN1 format as specified in RFC 8152.
+ *    If an OEM private key is available: it is signed by the OEM private key.
+ *    The signature must be raw signature bytes.
  * @param[in,out] public_key_signature_size: on input, size of the caller's
  *    public_key_signature buffer. On output, the number of bytes written into
  *    the buffer.