diff --git a/CHANGES b/CHANGES
index 0e54372..c5cd00a 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3,6 +3,12 @@
 
  Changes between 0.9.6 and 0.9.7  [xx XXX 2000]
 
+  *) Change OCSP_cert_to_id() to tolerate a NULL subject certificate and
+     OCSP_cert_id_new() a NULL serialNumber. This allows a partial certificate
+     ID to be generated from the issuer certificate alone which can then be
+     passed to OCSP_id_issuer_cmp().
+     [Steve Henson]
+
   *) New compilation option ASN1_ITEM_FUNCTIONS. This causes the new
      ASN1 modules to export functions returning ASN1_ITEM pointers
      instead of the ASN1_ITEM structures themselves. This adds several
diff --git a/crypto/ocsp/ocsp_lib.c b/crypto/ocsp/ocsp_lib.c
index 4cdc5f0..0ddf1b2 100644
--- a/crypto/ocsp/ocsp_lib.c
+++ b/crypto/ocsp/ocsp_lib.c
@@ -80,8 +80,16 @@
 #ifndef OPENSSL_NO_SHA1
 	if(!dgst) dgst = EVP_sha1();
 #endif
-	iname = X509_get_issuer_name(subject);
-	serial = X509_get_serialNumber(subject);
+	if (subject)
+		{
+		iname = X509_get_issuer_name(subject);
+		serial = X509_get_serialNumber(subject);
+		}
+	else
+		{
+		iname = X509_get_subject_name(issuer);
+		serial = NULL;
+		}
 	ikey = X509_get0_pubkey_bitstr(issuer);
 	return OCSP_cert_id_new(dgst, iname, ikey, serial);
 }
@@ -118,9 +126,12 @@
 	EVP_Digest(issuerKey->data, issuerKey->length, md, &i, dgst);
 
 	if (!(ASN1_OCTET_STRING_set(cid->issuerKeyHash, md, i))) goto err;
-	
-	if (cid->serialNumber != NULL) ASN1_INTEGER_free(cid->serialNumber);
-	if (!(cid->serialNumber = ASN1_INTEGER_dup(serialNumber))) goto err;
+
+	if (serialNumber)
+		{
+		ASN1_INTEGER_free(cid->serialNumber);
+		if (!(cid->serialNumber = ASN1_INTEGER_dup(serialNumber))) goto err;
+		}
 	return cid;
 digerr:
 	OCSPerr(OCSP_F_CERT_ID_NEW,OCSP_R_DIGEST_ERR);