diff --git a/Modules/Core/Common/include/itkProcessObject.h b/Modules/Core/Common/include/itkProcessObject.h
index 2db949e9eb0..9d5649cbcb0 100644
--- a/Modules/Core/Common/include/itkProcessObject.h
+++ b/Modules/Core/Common/include/itkProcessObject.h
@@ -32,6 +32,7 @@
 #include "itkObjectFactory.h"
 #include "itkNumericTraits.h"
 #include "itkThreadSupport.h"
+#include "itkIntTypes.h"
 #include <vector>
 #include <map>
 #include <set>