diff --git a/Eigen/Core b/Eigen/Core
index 37356d391..a2d66c6b8 100644
--- a/Eigen/Core
+++ b/Eigen/Core
@@ -77,6 +77,10 @@
 
 namespace Eigen {
 
+// we use size_t frequently and we'll never remember to prepend it with std:: everytime just to
+// ensure QNX/QCC support
+using std::size_t;
+
 /** \defgroup Core_Module Core module
   * This is the main module of Eigen providing dense matrix and vector support
   * (both fixed and dynamic size) with all the features corresponding to a BLAS library
@@ -147,10 +151,6 @@ namespace Eigen {
 #include "src/Core/Part.h"
 #include "src/Core/CacheFriendlyProduct.h"
 
-// we use size_t frequently and we'll never remember to prepend it with std:: everytime just to
-// ensure QNX/QCC support
-using std::size_t;
-
 } // namespace Eigen
 
 #include "src/Core/util/EnableMSVCWarnings.h"