diff --git a/library/xtea.c b/library/xtea.c
index 9404927..2cb2f30 100644
--- a/library/xtea.c
+++ b/library/xtea.c
@@ -111,6 +111,7 @@
     return( 0 );
 }
 
+#if defined(POLARSSL_CIPHER_MODE_CBC)
 /*
  * XTEA-CBC buffer encryption/decryption
  */
@@ -159,6 +160,7 @@
 
     return( 0 );
 }
+#endif /* POLARSSL_CIPHER_MODE_CBC */
 #endif /* !POLARSSL_XTEA_ALT */
 
 #if defined(POLARSSL_SELF_TEST)