diff --git a/src/utils/rclionice.cpp b/src/utils/rclionice.cpp
index 31072cb2..c5a01bb2 100644
--- a/src/utils/rclionice.cpp
+++ b/src/utils/rclionice.cpp
@@ -15,6 +15,7 @@
  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  */
 #include <stdio.h>
+#include <unistd.h>
 
 #include "rclionice.h"
 #include "execmd.h"