diff --git a/c-programming/math/opt_int_div.h b/c-programming/math/opt_int_div.h
index 9ab511c..15b48e8 100644
--- a/c-programming/math/opt_int_div.h
+++ b/c-programming/math/opt_int_div.h
@@ -3,6 +3,8 @@
  *
  * "Optimized integer division": A header-only library
  *
+ * NOTE: This code will work only on a computer that uses bits.
+ *
  * Author: Intel A80486DX2-66
  * License: Creative Commons Zero 1.0 Universal
  */