diff --git a/src/pk/dsa/dsa_verify_hash.c b/src/pk/dsa/dsa_verify_hash.c
index f3c2235..b13caf9 100644
--- a/src/pk/dsa/dsa_verify_hash.c
+++ b/src/pk/dsa/dsa_verify_hash.c
@@ -47,7 +47,7 @@ int dsa_verify_hash_raw(         void   *r,          void   *s,
    }
 
    /* neither r or s can be null or >q*/
-   if (mp_iszero(r) == LTC_MP_YES || mp_iszero(s) == LTC_MP_YES || mp_cmp(r, key->q) != LTC_MP_LT || mp_cmp(s, key->q) != LTC_MP_LT) {
+   if (mp_cmp_d(r, 0) != LTC_MP_GT || mp_cmp_d(s, 0) != LTC_MP_GT || mp_cmp(r, key->q) != LTC_MP_LT || mp_cmp(s, key->q) != LTC_MP_LT) {
       err = CRYPT_INVALID_PACKET;
       goto error;
    }