diff --git a/crypto/x509/v3_utl.c b/crypto/x509/v3_utl.c
index 4fd1f2cd60..5c63d2d9d8 100644
--- a/crypto/x509/v3_utl.c
+++ b/crypto/x509/v3_utl.c
@@ -529,17 +529,25 @@ static int append_ia5(STACK_OF(OPENSSL_STRING) **sk,
     /* First some sanity checks */
     if (email->type != V_ASN1_IA5STRING)
         return 1;
-    if (!email->data || !email->length)
+    if (email->data == NULL || email->length == 0)
+        return 1;
+    if (memchr(email->data, 0, email->length) != NULL)
         return 1;
     if (*sk == NULL)
         *sk = sk_OPENSSL_STRING_new(sk_strcmp);
     if (*sk == NULL)
         return 0;
+
+    emtmp = OPENSSL_strndup((char *)email->data, email->length);
+    if (emtmp == NULL)
+        return 0;
+
     /* Don't add duplicates */
-    if (sk_OPENSSL_STRING_find(*sk, (char *)email->data) != -1)
+    if (sk_OPENSSL_STRING_find(*sk, emtmp) != -1) {
+        OPENSSL_free(emtmp);
         return 1;
-    emtmp = OPENSSL_strdup((char *)email->data);
-    if (emtmp == NULL || !sk_OPENSSL_STRING_push(*sk, emtmp)) {
+    }
+    if (!sk_OPENSSL_STRING_push(*sk, emtmp)) {
         OPENSSL_free(emtmp); /* free on push failure */
         X509_email_free(*sk);
         *sk = NULL;