diff --git a/pixel.c b/pixel.c

--- a/pixel.c
+++ b/pixel.c
@@ -19,6 +19,10 @@
 #include <fcntl.h>
 #include "libg15render.h"

+#include <math.h>
+#include <stdlib.h>
+#include <unistd.h>
+
 void
 swap (int *x, int *y)
 {