diff -urN urg-0.8.11/src/cpp/system/LockGuard.h urg-0.8.11.gcc46/src/cpp/system/LockGuard.h
--- urg-0.8.11/src/cpp/system/LockGuard.h	2009-05-05 10:56:20.000000000 +0200
+++ urg-0.8.11.gcc46/src/cpp/system/LockGuard.h	2011-02-11 00:05:31.879003805 +0100
@@ -11,6 +11,7 @@
 */
 
 #include <memory>
+#include <cstddef>
 
 
 namespace qrk
diff -urN urg-0.8.11/src/cpp/system/Lock.h urg-0.8.11.gcc46/src/cpp/system/Lock.h
--- urg-0.8.11/src/cpp/system/Lock.h	2009-05-05 10:56:20.000000000 +0200
+++ urg-0.8.11.gcc46/src/cpp/system/Lock.h	2011-02-11 00:05:21.741043813 +0100
@@ -11,6 +11,7 @@
 */
 
 #include "ConditionVariable.h"
+#include <cstddef>
 
 
 namespace qrk
diff -urN urg-0.8.11/src/cpp/system/Semaphore.h urg-0.8.11.gcc46/src/cpp/system/Semaphore.h
--- urg-0.8.11/src/cpp/system/Semaphore.h	2009-05-05 10:56:20.000000000 +0200
+++ urg-0.8.11.gcc46/src/cpp/system/Semaphore.h	2011-02-11 00:05:42.071963563 +0100
@@ -13,6 +13,7 @@
 */
 
 #include <memory>
+#include <cstddef>
 
 
 namespace qrk