diff --git a/library/aes.c b/library/aes.c
index 6456c54..a3835ce 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -769,6 +769,7 @@
     return( 0 );
 }
 
+#if defined(POLARSSL_CIPHER_MODE_CBC)
 /*
  * AES-CBC buffer encryption/decryption
  */
@@ -832,6 +833,7 @@
 
     return( 0 );
 }
+#endif /* POLARSSL_CIPHER_MODE_CBC */
 
 #if defined(POLARSSL_CIPHER_MODE_CFB)
 /*
@@ -947,6 +949,7 @@
       0xFF, 0x30, 0xB4, 0xEA, 0x21, 0x63, 0x6D, 0xA4 }
 };
 
+#if defined(POLARSSL_CIPHER_MODE_CBC)
 static const unsigned char aes_test_cbc_dec[3][16] =
 {
     { 0xFA, 0xCA, 0x37, 0xE0, 0xB0, 0xC8, 0x53, 0x73,
@@ -966,6 +969,7 @@
     { 0xFE, 0x3C, 0x53, 0x65, 0x3E, 0x2F, 0x45, 0xB5,
       0x6F, 0xCD, 0x88, 0xB2, 0xCC, 0x89, 0x8F, 0xF0 }
 };
+#endif /* POLARSSL_CIPHER_MODE_CBC */
 
 #if defined(POLARSSL_CIPHER_MODE_CFB)
 /*
@@ -1104,8 +1108,10 @@
     int i, j, u, v;
     unsigned char key[32];
     unsigned char buf[64];
-    unsigned char prv[16];
     unsigned char iv[16];
+#if defined(POLARSSL_CIPHER_MODE_CBC)
+    unsigned char prv[16];
+#endif
 #if defined(POLARSSL_CIPHER_MODE_CTR) || defined(POLARSSL_CIPHER_MODE_CFB)
     size_t offset;
 #endif
@@ -1170,6 +1176,7 @@
     if( verbose != 0 )
         printf( "\n" );
 
+#if defined(POLARSSL_CIPHER_MODE_CBC)
     /*
      * CBC mode
      */
@@ -1231,6 +1238,7 @@
 
     if( verbose != 0 )
         printf( "\n" );
+#endif /* POLARSSL_CIPHER_MODE_CBC */
 
 #if defined(POLARSSL_CIPHER_MODE_CFB)
     /*