https://github.com/tobez/validns/pull/71

Index: dnskey.c
--- dnskey.c.orig
+++ dnskey.c
@@ -145,6 +145,7 @@ int dnskey_build_pkey(struct rr_dnskey *rr)
 		unsigned int e_bytes;
 		unsigned char *pk;
 		int l;
+		BIGNUM *n, *e;
 
 		rsa = RSA_new();
 		if (!rsa)
@@ -165,11 +166,15 @@ int dnskey_build_pkey(struct rr_dnskey *rr)
 		if (l < e_bytes) /* public key is too short */
 			goto done;
 
-		rsa->e = BN_bin2bn(pk, e_bytes, NULL);
+		e = BN_bin2bn(pk, e_bytes, NULL);
 		pk += e_bytes;
 		l -= e_bytes;
 
-		rsa->n = BN_bin2bn(pk, l, NULL);
+		n = BN_bin2bn(pk, l, NULL);
+		if (!e || !n)
+			goto done;
+
+		RSA_set0_key(rsa, n, e, NULL);
 
 		pkey = EVP_PKEY_new();
 		if (!pkey)