diff --git a/src/crypto/tls_openssl.c b/src/crypto/tls_openssl.c
index d8c8c56b5..a4c71dc06 100644
--- a/src/crypto/tls_openssl.c
+++ b/src/crypto/tls_openssl.c
@@ -3167,7 +3167,7 @@ static int ocsp_resp_cb(SSL *s, void *arg)
 				sk_X509_free(certs);
 				certs = NULL;
 			}
-			if (conn->peer_issuer_issuer) {
+			if (certs && conn->peer_issuer_issuer) {
 				cert = X509_dup(conn->peer_issuer_issuer);
 				if (cert && !sk_X509_push(certs, cert)) {
 					tls_show_errors(