diff --git a/library/x509.c b/library/x509.c
index 3114076..48c11ef 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -137,6 +137,7 @@
     return( 0 );
 }
 
+#if defined(POLARSSL_RSASSA_PSS_CERTIFICATES)
 /*
  * HashAlgorithm ::= AlgorithmIdentifier
  *
@@ -329,6 +330,7 @@
 
     return( 0 );
 }
+#endif /* POLARSSL_RSASSA_PSS_CERTIFICATES */
 
 /*
  *  AttributeTypeAndValue ::= SEQUENCE {