diff --git a/library/x509.c b/library/x509.c
index adb025c..73e1347 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -592,7 +592,7 @@
         *sig_opts = (void *) pss_opts;
     }
     else
-#endif
+#endif /* POLARSSL_X509_RSASSA_PSS_SUPPORT */
     {
         /* Make sure parameters are absent or NULL */
         if( ( sig_params->tag != ASN1_NULL && sig_params->tag != 0 ) ||