diff --git a/include/polarssl/x509.h b/include/polarssl/x509.h
index a21c1f0..e11bd90 100644
--- a/include/polarssl/x509.h
+++ b/include/polarssl/x509.h
@@ -281,7 +281,7 @@
 #if defined(POLARSSL_RSASSA_PSS_CERTIFICATES)
 int x509_get_rsassa_pss_params( const x509_buf *params,
                                 md_type_t *md_alg, md_type_t *mgf_md,
-                                int *salt_len, int *trailer_field );
+                                int *salt_len );
 #endif
 int x509_get_sig( unsigned char **p, const unsigned char *end, x509_buf *sig );
 int x509_get_sig_alg( const x509_buf *sig_oid, const x509_buf *sig_params,