diff --git a/common/network/TcpSocket.cxx b/common/network/TcpSocket.cxx
index 3212ace..5dd2428 100644
--- a/common/network/TcpSocket.cxx
+++ b/common/network/TcpSocket.cxx
@@ -37,6 +37,7 @@
 #include <fcntl.h>
 #endif
 
+#include <stdlib.h>
 #include <network/TcpSocket.h>
 #include <rfb/util.h>
 #include <rfb/LogWriter.h>