diff --git a/crypto/pem/pvkfmt.c b/crypto/pem/pvkfmt.c
index 348a92b64a..adf2914433 100644
--- a/crypto/pem/pvkfmt.c
+++ b/crypto/pem/pvkfmt.c
@@ -274,6 +274,9 @@ static EVP_PKEY *b2i_dss(const unsigned char **in,
         if (!read_lebn(&p, 20, &priv_key))
             goto memerr;
 
+        /* Set constant time flag before public key calculation */
+        BN_set_flags(priv_key, BN_FLG_CONSTTIME);
+
         /* Calculate public key */
         pub_key = BN_new();
         if (pub_key == NULL)