diff --git a/space/src/main.cpp b/space/src/main.cpp
index 4f4ae82db2..d88c4fd004 100644
--- a/space/src/main.cpp
+++ b/space/src/main.cpp
@@ -8,6 +8,7 @@
 
 #include <iostream>
 #include <cstdio>
+#include <stdlib.h>
 #include "TreeNode.h"
 #include "UDPSocket.h"