diff --git a/properties.m b/properties.m
index 37bf4cc..c187f98 100644
--- a/properties.m
+++ b/properties.m
@@ -4,7 +4,6 @@
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
-#include <unistd.h>
 #include "class.h"
 #include "properties.h"
 #include "spinlock.h"