diff --git a/include/polarssl/hmac_drbg.h b/include/polarssl/hmac_drbg.h
index 709f25d..2d765d5 100644
--- a/include/polarssl/hmac_drbg.h
+++ b/include/polarssl/hmac_drbg.h
@@ -265,7 +265,7 @@
  *                      POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG
  */
 int hmac_drbg_update_seed_file( hmac_drbg_context *ctx, const char *path );
-#endif
+#endif /* POLARSSL_FS_IO */
 
 
 #if defined(POLARSSL_SELF_TEST)