diff --git a/library/pk.c b/library/pk.c
index 6d29663..e0dedec 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -367,7 +367,7 @@
             return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
 
         ret = mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_pk_rsa( *ctx ),
-                NULL, NULL, MBEDTLS_RSA_PUBLIC,
+                NULL, MBEDTLS_RSA_PUBLIC,
                 md_alg, (unsigned int) hash_len, hash,
                 pss_opts->mgf1_hash_id,
                 pss_opts->expected_salt_len,