diff --git a/src/include/lib.h b/src/include/lib.h
index 0d6fdb14be..46d8b02112 100644
--- a/src/include/lib.h
+++ b/src/include/lib.h
@@ -40,6 +40,8 @@ void hexdump32(char LEVEL, const void *d, size_t len);
  *
  * Defined in src/lib/hexstrtobin.c
  * Ignores non-hex characters in the string.
+ * Ignores the last hex character if the number of hex characters in the string
+ * is odd.
  * Returns the number of bytes that have been put in the buffer.
  */
 size_t hexstrtobin(const char *str, uint8_t *buf, size_t len);