diff --git a/AerofoilPortable/GpThreadEvent_Cpp11.cpp b/AerofoilPortable/GpThreadEvent_Cpp11.cpp
index 2e7ab51..c8ce5d7 100644
--- a/AerofoilPortable/GpThreadEvent_Cpp11.cpp
+++ b/AerofoilPortable/GpThreadEvent_Cpp11.cpp
@@ -1,5 +1,7 @@
 #include "GpThreadEvent_Cpp11.h"
 
+#include <stdlib.h>
+
 GpThreadEvent_Cpp11::GpThreadEvent_Cpp11(bool autoReset, bool startSignaled)
 	: m_flag(startSignaled)
 	, m_autoReset(autoReset)
diff --git a/AerofoilX/GpLogDriver_X.cpp b/AerofoilX/GpLogDriver_X.cpp
index 1d5267a..16da415 100644
--- a/AerofoilX/GpLogDriver_X.cpp
+++ b/AerofoilX/GpLogDriver_X.cpp
@@ -4,6 +4,7 @@
 #include "GpApplicationName.h"
 #include "GpIOStream.h"
 
+#include <stdlib.h>
 #include <time.h>
 #include <cstring>
 
diff --git a/PortabilityLayer/ZipFileProxy.cpp b/PortabilityLayer/ZipFileProxy.cpp
index a4d9f44..a9003d4 100644
--- a/PortabilityLayer/ZipFileProxy.cpp
+++ b/PortabilityLayer/ZipFileProxy.cpp
@@ -10,6 +10,7 @@
 #include "DeflateCodec.h"
 
 #include <algorithm>
+#include <stdlib.h>
 
 namespace
 {