--- a/security/pkix/test/lib/pkixtestutil.h
+++ b/security/pkix/test/lib/pkixtestutil.h
@@ -67,18 +67,19 @@ enum Version { v1 = 0, v2 = 1, v3 = 2 };
 // If issuerPrivateKey is null, then the certificate will be self-signed.
 // Parameter order is based on the order of the attributes of the certificate
 // in RFC 5280.
 //
 // The return value, if non-null, is owned by the arena in the context and
 // MUST NOT be freed.
 SECItem* CreateEncodedCertificate(PLArenaPool* arena, long version,
                                   SECOidTag signature, long serialNumber,
-                                  const char* issuerASCII, PRTime notBefore,
-                                  PRTime notAfter, const char* subjectASCII,
+                                  const SECItem* issuerNameDER,
+                                  PRTime notBefore, PRTime notAfter,
+                                  const SECItem* subjectNameDER,
                      /*optional*/ SECItem const* const* extensions,
                      /*optional*/ SECKEYPrivateKey* issuerPrivateKey,
                                   SECOidTag signatureHashAlg,
                           /*out*/ ScopedSECKEYPrivateKey& privateKey);
 
 MOZILLA_PKIX_ENUM_CLASS ExtensionCriticality { NotCritical = 0, Critical = 1 };
 
 // The return value, if non-null, is owned by the arena and MUST NOT be freed.