--- a/strerr.h
+++ b/strerr.h
@@ -1,3 +1,5 @@
+#include <errno.h>
+
 #ifndef STRERR_H
 #define STRERR_H
 
--- a/substdio.h
+++ b/substdio.h
@@ -1,3 +1,5 @@
+#include <errno.h>
+
 #ifndef SUBSTDIO_H
 #define SUBSTDIO_H
 
--- a/speed.c
+++ b/speed.c
@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <stdlib.h>
 #include "fftr4.h"
 #include "fftr8.h"
 #include "fftc4.h"
--- a/accuracy2.c
+++ b/accuracy2.c
@@ -1,3 +1,4 @@
+#include <stdlib.h>
 #include <stdio.h>
 #include <math.h>
 #include "fftc4.h"
--- a/accuracy.c
+++ b/accuracy.c
@@ -1,3 +1,4 @@
+#include <stdlib.h>
 #include <stdio.h>
 #include <math.h>
 #include "fftc4.h"