diff --git a/processor/head.m4 b/processor/head.m4
index 1b3df70..648c55e 100644
--- a/processor/head.m4
+++ b/processor/head.m4
@@ -1,6 +1,6 @@
 dnl {{{ === program start ========================================
 divert(0)
-EXPORT(`#include <stddef.h>') dnl for ptrdiff_t
+EXPORT(`#include <stddef.h>')
 #include <string.h>
 #include <stdio.h>