diff --git a/Source/util.h b/Source/util.h
index 77e06575..f5757750 100644
--- a/Source/util.h
+++ b/Source/util.h
@@ -27,6 +27,7 @@
 #ifndef _WIN32
 #  include <iconv.h>
 #  include <stdio.h>
+#  include <unistd.h>
 #endif